Taxation of Couples in Switzerland: What if we are all looking in the wrong direction?

To demand that a tax system be perfectly just is to require a collective work to satisfy interests that, by definition, never fully converge. It is to ask the law—a general and abstract instrument—to capture the infinite variety of particular situations. It is, in short, to pursue a horizon that recedes as one approaches it.

Switzerland is about to vote on individual taxation of spouses, presented as the remedy to a widely denounced injustice: the so-called “marriage penalty.” The diagnosis seems settled, the remedy consensual. Yet, if one consents to slow down and examine the very foundations of the problem, doubt sets in. What if the ailment we seek to cure is not what we think it is? What if, in correcting one asymmetry, we merely shift its weight onto other shoulders?

This article is an invitation to that doubt. It does not claim to hold the definitive answer—for such an answer, as we shall see, probably does not exist. Rather, it seeks to demonstrate that the debate suffers from a flaw in perspective: we are looking in the wrong direction. Joint taxation of spouses, far from being the source of the problem, rests on a constitutional and economic logic more solid than commonly believed (Section 1). It is the absence of joint taxation of cohabiting partners that creates the true breach of equality—an absence that neither the objection based on civil law attachment (Section 2) nor that founded on legal certainty and the constraints of mass administration (Section 3) fully justify. Beyond this first fracture, a second deserves examination: that which opposes single-income families and dual-income families, revealing a system whose architecture always adapts too late to respond to socio-economic evolution (Section 4), and whose very conception of taxable income—more flexible than commonly believed—would offer still unexplored avenues (Section 5). The question then arises as to why the taxpayer cannot simply choose their regime, a question less naive than it appears given the many structural choices the system already permits (Section 6). Finally, we must recognise that these imperfections persist due to constraints inherent to our incomplete federalism and our constitutionalism (Section 7), as well as to the very nature of the democratic compromise characteristic of positive law (Section 8). Are we then condemned to live in a tax system whose injustice is inherent, structural, irremediable (Section 9)?

This observation could discourage. It should, on the contrary, awaken a form of demanding lucidity. For if perfect tax justice is a mirage, the democratic process that brings us closer to it through successive approximations is quite real. And it is in this movement—imperfect, slow, sometimes contradictory—that perhaps lies the only form of justice to which a system of positive law can reasonably aspire.

1. The Taxpayer’s Economic Capacity

The dominant analysis starts from the postulate that joint taxation of spouses is, in itself, the source of the injustice. This article intends to demonstrate that this reading is incomplete, even misleading. The problem lies not so much in the fact that spouses are taxed jointly, but in the fact that cohabiting partners are not—even though their economic reality would warrant it. In other words, we are all looking in the wrong direction.

The Swiss tax system rests on a fundamental constitutional principle: that of taxation according to the taxpayer’s economic capacity. This principle, anchored in the Federal Constitution, means that each person must contribute to public expenses in proportion to their actual means. Those who have greater resources pay more; those who have less, pay less. It is a rule of apparent simplicity, but whose application raises formidable questions as soon as one considers life as a couple.

Now, two people who share a common household do not live as two isolated individuals. Spouses pool a significant portion of their expenses—housing, food, insurance, current charges—and thereby achieve economies of scale that a single person does not enjoy. A shared rent costs less per person than a rent borne alone; household insurance covers two people without the premium doubling. These economies are not trivial: they substantially modify the actual standard of living of each spouse. It would therefore be artificial, in assessing a spouse’s economic capacity, to disregard this community of expenses. This is why tax law treats spouses as an economic unit and subjects them to joint taxation, adding their income and wealth to determine their overall contributive capacity. This approach is not an invention of the ordinary legislator: it flows directly from the consistent case law of the Federal Supreme Court, which has always held that the common standard of living of spouses requires a joint measure of their ability to contribute to public expenses.

If one confines oneself to this comparison—spouses versus two individuals with no connection—joint taxation appears not only justified but logically necessary. Two strangers each bear their own expenses independently. Their respective economic capacity is measured individually, without any adjustment. Spouses, by contrast, benefit from pooling that increases their actual capacity: it is therefore coherent to tax them together.

However, this justification loses much of its force when the point of comparison is shifted. For spouses are not the only ones who share a household. Cohabiting partners—that is, unmarried couples living together—enjoy exactly the same economies of scale. They share the same housing, bear the same common expenses, and enjoy a standard of living comparable to that of a married couple in an equivalent economic situation. Their economic capacity, strictly speaking, should also be measured jointly. Yet this is not the case: cohabiting partners are taxed individually, each on their own, as if they were two unrelated persons. This differential treatment creates a manifest asymmetry. Married spouses, whose incomes are combined, bear the full brunt of the progressive tax scale—a mechanism that increases the tax rate as income rises. Cohabiting partners, by contrast, escape this increased progression since each is taxed only on their personal income. With identical total incomes, the married couple therefore pays more than the unmarried couple. This is what is commonly called the “marriage penalty.”

“The asymmetry lies not in the fact that spouses are taxed jointly, but in the fact that cohabiting partners are not.”

It would be tempting to conclude that joint taxation of spouses is inherently unjust and must be abandoned. This is, moreover, the reasoning underlying the reform currently proposed in favour of individual taxation of spouses. And it is true that this reform would restore, at first glance, a certain equality between married and cohabiting couples. But if one pushes the analysis a little further, one realises that this solution resolves only part of the problem—and perhaps not the right part.

Indeed, individual taxation of spouses, like that of cohabiting partners, poses a fundamental conceptual difficulty. If two people who share a household genuinely have an increased economic capacity compared to isolated individuals—and this is indeed the case, whether they are married or not—then taxing each of them separately, as singles, amounts to ignoring a tangible economic reality. Neither individual taxation of spouses nor that of cohabiting partners is fully justified when compared with truly single persons.

“Individual taxation does not create more justice; it simply shifts the inequality.”

Consequently, if one seeks to correct this inequality, it would in reality be more just and more coherent to extend joint taxation to cohabiting partners than to dismantle that of spouses. The question that then arises is why the legislator has not done so—and whether it could. But if joint taxation is justified by the economic community of life, and if cohabiting partners also share such a community, the question naturally arises: why not apply the same regime to them?

2. The Biased Attachment to Civil Law

The first objection to joint taxation of cohabiting partners, substantial in appearance, concerns the nature of the economic link between them. For married spouses, mutual support is a legal obligation; for cohabiting partners, it is a matter of will alone. How, then, can identical tax treatment be justified for legally distinct situations?

The argument deserves attention, but it loses much of its force when one observes how tax law actually treats support obligations.

First, the matrimonial property regime chosen by the spouses—participation in acquired property, separation of property, or community of property—considerably modulates the actual extent of economic sharing within the couple. Yet tax law expressly ignores these distinctions: joint taxation applies regardless of the matrimonial regime. Added to this is the infinitely diverse reality on the ground: some spouses share everything, others practise a separation of income to a large extent. Tax law abstracts from this variety.

Second, the tax system already recognises reliefs based on support that is not legally obligatory. Social deductions and parental tax scales—at federal level—or other equivalent measures—at cantonal level—benefit taxpayers who support relatives, including when this support exceeds what civil law requires. Economic reality prevails, here again, over legal obligation.

Third, and perhaps most revealing, tax law sometimes ignores the maintenance obligation even where it exists. Support for an adult child in education, although legally obligatory under certain conditions, gives rise to no alimony deduction beyond the child’s majority. On the other hand, social deductions and the parental tax scale at federal level continue to apply well beyond majority, including when support is no longer obligatory. The system thus enshrines a remarkable decoupling between civil obligation and tax treatment.

“The voluntary nature of support between cohabiting partners does not, in itself, constitute a decisive obstacle to their joint taxation.”

It follows from the foregoing that the voluntary nature of support between cohabiting partners does not, in itself, constitute a decisive obstacle to their joint taxation. The choice made by a couple to share their economic means must be opposable to them. The fact of having chosen to pool resources without formally obligating oneself should not prevent the fiscal recognition of this economic community, just as having chosen to help relatives beyond the legal obligation already allows, in our system, consideration that the taxpayer’s economic capacity is thereby reduced.

3. Legal Certainty and Mass Administration

The second objection to joint taxation of cohabiting partners concerns the absence of formal registration of their union. Unlike marriage, cohabitation is not registered with the civil registry, so the tax administration does not have, at first glance, an objective and easily verifiable criterion to identify the couples concerned. The argument is attractive in its simplicity, but it does not withstand close examination.

Every tax rule must reconcile two sometimes contradictory imperatives: material accuracy and practicability. The law, in its primary vocation, aims to establish legal certainty and predictability. This is why it is made public. Moreover, tax authorities, as mass administrations, must show a certain pragmatism in applying the law. It is precisely in this spirit that the tax legislator readily uses flat rates, caps, and thresholds to avoid disproportionately burdensome calculations.

Indeed, our tax system does not blindly adhere to legal forms when assessing economic capacity. The most telling example is that of married spouses who are de facto separated: although their marriage subsists legally, they cease to be taxed jointly once the community of life has effectively ended. The legislator here values factual and economic reality more than legally formal reality. It does require, of course, that the end of the community of life be objectively provable and observable to third parties.

“It is economic substance, not the legal wrapper, that determines the applicable regime.”

It will be objected that this analysis of the common household in the economic sense only applies, in practice, at the moment of the breakdown of a previously formalised union, and not prior to its constitution. The administration, it will be said, only undertakes this verification because a marriage existed, providing it with a starting point. The argument is not decisive, however, for two reasons.

First, the concept of common household produces tax effects well before—and well beyond—the formalisation of the union. When a couple marries, the spouses are taxed jointly for the entire tax period concerned, whether the marriage was celebrated in January or December. The system thus proceeds from the idea that the economic community of life existed well before its formalisation, and that it would be artificial to take account of it only from the day of the ceremony. Symmetrically, divorce or de facto separation results in separate taxation for the entire tax year, regardless of when it occurs. Here again, it is considered that the economic community of life ended before the formal break. This logic is moreover reinforced by the treatment given to the death of a spouse, which causes a break in the tax period: the legislator clearly intended to draw a distinction, presuming that the economic community lasted until the very day of death, hence the need for joint taxation limited to that date.

Second, and this is the essential point, the indicators of an economic community of life between cohabiting partners are neither rare nor difficult to establish. Joint bank accounts, jointly owned real estate or jointly signed lease agreements, joint insurance—all objective and verifiable elements. Analytical technologies and modern databases make it possible to identify such indicators with increasing speed and reliability. Moreover, a system of joint taxation of cohabiting partners could perfectly well be designed as optional, allowing couples who wish to file a joint return rather than two separate ones. Such a mechanism would simultaneously reduce the workload of the administration and that of taxpayers. And it should be borne in mind that only a marginal minority seeks to evade tax; the vast majority of taxpayers comply with the rules honestly, if only for fear of penalties. Ultimately, our system already has the conceptual tools and practical mechanisms necessary to give primacy to economic reality over legal reality.

It is worth noting an irony that the current debate largely overlooks. The proposed reform in favour of individual taxation of spouses, far from lightening the workload of tax administrations, risks considerably increasing it. Where the current system processes a married couple by means of a single return and a single assessment, individual taxation would require processing two separate returns, the often complex and contestable allocation of joint income and deductions between the two spouses, and the multiplication of assessment decisions and, potentially, objection procedures. On a national scale, this would mean the tax authorities being asked to absorb a near-doubling of the volume of files relating to married taxpayers—without the human and technical resources of these administrations growing in the same proportions. The paradox is striking: administrative pragmatism is readily invoked to refuse joint taxation of cohabiting partners, while promoting a reform that precisely contradicts that same pragmatism. It is the extension of joint taxation to cohabiting partners that would truly serve this imperative of practicability: by allowing unmarried couples to file a joint return, the total number of returns to be processed would be reduced, the attribution of deductions linked to the common household would be simplified, and administrative treatment would be aligned with economic reality—all without requiring administrations to multiply their capacities.

In sum, practical considerations do not truly oppose joint taxation of cohabiting partners. The objection based on the absence of formalisation runs up against a system that, in many areas, already gives primacy to substance over form. If we can thus resolve the supposed “inequality” between cohabiting partners and spouses, what about the inequality between traditional families—where only one spouse works full-time—and modern families—where both spouses work full-time?

4. De Lege Lata or De Lege Ferenda?

If one accepts that joint taxation of spouses is justified with regard to the principle of economic capacity, and that the true inequality lies in the treatment of cohabiting partners rather than that of spouses, another question deserves to be asked. Within married couples themselves, does the current system treat equitably so-called “traditional” families, where only one spouse engages in gainful activity, and so-called “modern” families, where both spouses work full-time? Examining this question requires addressing two distinct problems: that of the system’s adaptation to socio-economic evolution, and the more fundamental one of the tax qualification of work performed in the home.

It is an undeniable fact that the economic structure of households has profoundly changed, and continues to evolve toward dual full-time employment. Historically, the dominant model was that of a single income, or at least a primary income, per couple. Whether this phenomenon is attributed to social factors—the traditional place assigned to women in the home—or to economic factors—the once more widespread possibility of providing for a family on a single salary—the observation is the same: dual-income couples are now increasingly numerous. This transformation of economic reality is not without consequence on the tax level.

The question then arises as to whether the joint taxation system, as designed, structurally penalises dual-income couples. Indeed, the addition of two incomes—subject to a common progressive scale—mechanically results in a higher marginal tax rate than if each income were taxed separately.

The legislator has not entirely ignored this difficulty. There exist, at both federal and cantonal levels, corrective mechanisms specifically intended to mitigate the effect of joint progression for dual-income couples. One thinks notably of the dual-income deduction, or the right to deduct third-party childcare costs, which is a function of the combined activity rate of both spouses. The very existence of these instruments reveals that the legislator has recognised the need to distinguish, among jointly taxed couples, those where both partners engage in gainful activity from those where only one does.

However, this recognition remains partial. The social deduction granted to married couples and the reduced scale applicable to them at federal level—as well as the various reliefs provided by the cantons—apply indiscriminately, without any consideration for the distribution of activity within the couple. The system thus does not truly take into account the added value provided by the presence of a spouse at home, even though this unpaid contribution constitutes a real economic advantage that dual-income families do not enjoy, or at least not to the same extent.

“The tax architecture is always late in responding coherently to modern reality.”

The observation is therefore nuanced. The system has indeed evolved in the right direction by providing mitigation and adjustment mechanisms according to social reality—the very notion of “social deductions” bears witness to this. But these adjustments remain insufficient and, in truth, the system was already poorly designed even before socio-economic evolution accentuated its flaws. The problem is not so much that modern reality is ignored; it is that the tax architecture was never designed to respond to it coherently.

Given the evolution of our socio-economic reality, the real question thus arises: are we building tax law for the past, for today, or for tomorrow? The legislator has manifestly made an effort to mitigate the fiscal discordance between single-income and dual-income families. The very existence of corrective mechanisms such as the dual-income deduction or the consideration of childcare costs testifies to the recognition, at least implicit, of this inequality. But recognising an imbalance and correcting it satisfactorily are two different things. Current tools remain partial palliatives, applied heterogeneously across cantons, and which fail to eliminate the distortions inherent in a system built on socio-economic premises now largely outdated.

5. The Concept and Realisation of Income

If one pushes the reasoning further, another question, more audacious, arises: should we not, to restore a certain equity between the two family models, fiscally recognise the value of work performed in the home by the spouse without gainful activity or working part-time? To answer this, one must return to the very concept of taxable income—a concept that, in Swiss tax law, is far from being as clear as one might think.

It is, indeed, virtually impossible to give a unitary and exhaustive definition of income. The Federal Supreme Court itself acknowledges that it is easier to say what does not constitute income than to say what does. The classical income-product theory, which envisaged income as a regular monetary flow, has long since proved insufficient. Today we tax dividends, pension benefits, insurance payments, bonuses—all sources that do not correspond to a regular flow in the strict sense. The net wealth accretion theory has allowed the concept to be broadened, but it too encounters its limits: a capital gain created for oneself is in principle not taxable, nor is the mere appreciation of wealth, because Swiss tax law, thirdly, retains the principle of market realisation.

It is precisely on this ground that the case of the stay-at-home spouse becomes relevant. The spouse who does not engage in gainful activity—or only part-time—undeniably contributes to the couple’s economic well-being through work in kind: household tasks, child-rearing, home management. This work represents real economic value that the other spouse, the one who works, does not need to acquire on the market. Yet this value is not treated as taxable income, precisely because it is not exchanged for money on a market. The realisation principle seems to oppose it.

Yet our tax system already knows notable exceptions to this principle. The most striking example was imputed rental value—admittedly recently abolished. The owner who lived in their own home was taxed on a fictitious income, corresponding to the rent they could have received if they had let the property. The Federal Supreme Court confirmed that this taxation, although manifestly contrary to the principle of market realisation, was not unconstitutional. This case law established an important precedent: the taxpayer’s economic capacity is not measured exclusively by monetary flows or market transactions.

“The taxation of economic value in the absence of any market exchange is not a concept foreign to Swiss tax law.”

Other mechanisms point in the same direction. The principle of systematic realisation of hidden reserves constitutes an eloquent example. When an asset passes from a taxable regime to an exempt regime, the “potential” income—that is, the accumulated but not yet realised capital gain—is fictitiously realised and subjected to tax, in the absence of any actual market exchange.

The taxation of economic value before its exchange on the market, or even without such an exchange ever occurring, is therefore not a concept foreign to Swiss tax law. Nothing, on the constitutional level, would a priori prohibit the fiscal recognition of the value of work performed in the home. That said, the legislator has taken a different path: rather than taxing the value of domestic work, it has chosen to compensate for its absence through reliefs benefiting dual-income families—notably through deductible childcare costs and the dual-income deduction. This is a choice of tax policy, not a legal impossibility.

Consequently, if the inequalities between spouses and cohabiting partners, on the one hand, and between traditional and modern families, on the other, are recognised but imperfectly corrected, one must ask: why, despite these observations, does the system remain structurally unjust?

6. Extra-Fiscal Objectives

One might wonder why the taxpayer cannot simply choose their taxation regime. The question is not as naive as it seems. Indeed, our tax system already offers a multitude of structural choices to taxpayers, some of which are guided exclusively—or at least primarily—by tax considerations. The taxpayer chooses to carry on an activity as an employee or as a self-employed person. They organise their business as a sole proprietorship or as a corporation. They contribute to the third pillar or opt for alternative investments. They hold their property directly or through a real estate company. Each of these choices entails distinct tax consequences, sometimes considerable, and the system accepts them, even encourages them.

Moreover, the structural choices offered by tax law in terms of optimisation do not themselves escape family reality. On the contrary, they presuppose and favour it. Gifts and inheritances between spouses and between parents and descendants benefit, in most cantons, from total or near-total exemption from tax—an advantage from which cohabiting partners are largely excluded. This exemption notably allows better protection of life insurance and pension benefits accruing to the surviving spouse, thus consolidating the economic protection of the household even beyond death.

This observation moreover extends beyond the boundaries of direct taxation. Our social security system—that parafiscality too often forgotten in the analysis—provides specific benefits for widowers and widows, thereby recognising the economic loss represented by the disappearance of a spouse. Family allowances, whose increase precisely served as a political counterpart to secure the vote on TRAF, or income replacement allowances covering maternity, are all instruments by which the State actively promotes the family unit. If one consents to look beyond direct taxation alone and consider the legal order as a whole, the landscape is unambiguous: the State directs the behaviour and choices of taxpayers through a dual mechanism—subsidies and reliefs, on the one hand, taxation and contributions, on the other—and the family, in this framework, occupies a place that the legislator has deliberately chosen to favour.

The currently proposed reform moreover strikingly illustrates the confusion of extra-fiscal objectives that the legislator simultaneously pursues. On one side, individual taxation is presented as an instrument of economic emancipation: by eliminating the dissuasive effect of income aggregation, it intends to encourage women—for they are, in the vast majority of cases, those who reduce their activity rate—to join or intensify their presence in the labour market. The objective is explicitly behavioural: to push stay-at-home spouses toward employment. But on the other side, the same reform provides, at least at the federal level, a substantial increase in child deductions. Yet these two objectives enter into a contradiction that one struggles to ignore. Women are encouraged to work more while increasing reliefs linked to the presence of children—children whose birth and education are precisely made more difficult by the intensification of both parents’ professional activity. The legislator thus seems to want simultaneously to empty the home and fill it, to promote dual employment and compensate for its demographic consequences. This is a conflict of purposes that the political compromise masks without resolving.

“The legislator thus seems to want simultaneously to empty the home and fill it, to promote dual employment and compensate for its demographic consequences.”

To this first irony is added a second, perhaps more serious still, concerning a demographic group largely forgotten in the debate: retirees. Here are couples who have, for the most part, lived the bulk of their working lives under the model of the traditional single-income or primary-income family. Individual taxation, designed to encourage dual activity, offers them no prospect of adaptation: the spouse who did not engage in gainful activity—or only marginally—is not going to seek employment at retirement age. As for the idea that they might “find” a second pension where no professional career built one, it is pure fiction. These couples, who form a considerable portion of our population, will thus find themselves subject to a tax regime designed for a family model that was never theirs, without any possibility of deriving the expected benefits—and without the political debate having accorded them the attention that their number and vulnerability would command.

So what justifies the taxpayer not being able to decide whether to be taxed jointly or separately? Why is this particular choice denied to them? The answer lies, in part, in the structural limits of our legal order. But these limits are not so much substantive reasons as symptoms of a system that, by its very nature, cannot achieve perfection.

7. Federalism and Constitutionalism

The first of these symptoms is a federalism that stops halfway. The Federal Act on the Harmonisation of Direct Taxes imposes on the cantons the obligation of joint taxation of spouses and the overall progression of the tax scale. On the other hand, it scarcely legislates on social deductions or on the scales themselves. The cantons, aware of the need to provide reliefs according to family situation, attempt to counterbalance the socio-economic particularities of their taxpayers by various means: some adjust the scales, others use coefficients, still others use specific deductions. The result is a patchwork where having a family—a spouse, a child—in one canton or another engenders considerably different tax consequences. This is all the more significant as the cantonal tax burden is, in most cases, much heavier than the federal burden. The Confederation has obliged the cantons to take into account certain socio-economic factors, such as the existence of a family unit, without however following this logic through to its conclusion. And the real problem lies in the fact that the currently proposed reform risks repeating exactly the same error: in requiring the cantons to switch to individual taxation, the harmonisation act will likely remain silent on the reliefs that the cantons should adopt in return, even though the Confederation has provided for them. This is a characteristic manifestation of our incomplete federalism.

“A harmonisation that harmonises the obligation to collect, but not the obligation to temper.”

The second symptom is inherent to the very nature of the liberal state and its law. Tax law is not designed to lighten state power, but to found it. If the Constitution protects property, tax law is precisely what justifies its limitation by introducing taxes. The legislator thinks first of legitimising the collection of tax, and it is only in a second phase—often under the pressure of a popular referendum—that it sets about providing for exceptions, reliefs, and mitigations. This is why our tax law is generally clearer and more precise when it comes to taxing than when it comes to ensuring equality—or fairness—in that taxation.

The third symptom is the absence of abstract constitutional review. Unlike other countries, Switzerland has neither a specialised constitutional court nor a mechanism for preliminary and abstract review of the constitutionality of federal laws. The Federal Supreme Court does not rule, in the abstract, on the conformity of a law with the Constitution. It decides in concrete cases, with respect to identified parties, and it is only for them that its decision will be binding. Now, because the law must remain general and abstract, it inevitably contains gaps—sometimes intentional, sometimes resulting from the legislator’s unpredictability or even negligence in the face of certain particular situations. This is why case law and doctrine interpret laws, sometimes going so far that the interpretation contradicts the initial meaning of the text. The injustice of a tax system can therefore only be corrected case by case, over time, without the system as a whole being subject to a global and immediate challenge.

8. Positive Law

The fourth symptom, finally, is the democratic compromise itself. If Switzerland practises joint taxation of spouses as other countries do not, it also knows legislative referendums as other countries do not practise. The tax system is never merely a matter of pure law: it lies at the crossroads of economic motivations, social pressures, and political calculations. Holding company statuses are abolished and, after failing in a first vote, victory is achieved by increasing family allowances. VAT is raised while strengthening pension benefits. Tax rates are reduced in one canton and, in return, the tax value of real estate is reassessed. Each legislative choice is the product of debates, of opposing interests that end up agreeing at the price of mutual concessions.

“Democracy is not the regime where everyone is satisfied; it is the one where everyone gives something up to receive something else in return.”

If, in the legal domain, one often contrasts the naturalist school and the positivist school, it must be acknowledged that tax law is to a very large extent more positivist than naturalist, which explains the considerable differences observed from one country to another, from one generation to another, and even from one canton to another. This is our collective choice, the democratic choice. And it is in this choice, precisely, that lies both the source of imperfection and the only possible remedy.

It is in the nature of democratic compromise to decide in haste, under the pressure of the parliamentary calendar, referendum deadlines, and budgetary imperatives. Now, a decision made in haste is rarely a decision thought through in all its ramifications. The legislator, confronted with an identified problem—here, the marriage penalty—concentrates its energy on correcting this precise imbalance, without always measuring the shock waves that its reform will cause elsewhere in the system. This is the nature of any surgical intervention on a complex organism: one cures one organ, but weakens another.

And this phenomenon is not limited to the taxation of couples. It runs through our entire tax law with remarkable consistency. Wherever the legislator has made a choice, that choice has generated its own asymmetries. The wealthy expatriate or the foreign specialist benefits from deductions denied to the ordinary taxpayer, or even is subject to expenditure-based taxation—a regime of which the Swiss taxpayer can only dream—in the name of a higher interest: the country’s economic attractiveness. Private capital gains are exempt, in exchange—it is said—for the non-deductibility of losses, while wealth returns are fully taxed, albeit with symmetrically limited interest deductibility. Tax advantages are given to tied pension contributions to the detriment of simple bank investments that, economically, serve a comparable function. Transparency is imposed on collective real estate investments while corporations are subjected to economic double taxation that can only be imperfectly corrected. Each of these rules obeys its own internal logic; but their juxtaposition draws a landscape where the advantages of some are, invariably, the disadvantages of others.

“Every tax reform is a zero-sum game disguised as progress: what is granted to some is taken from others.”

This is a truth that one struggles to admit, but which imposes itself with relentless regularity. Each time a taxpayer obtains a relief, another can legitimately see it as an injustice toward them. Each time the tax burden of one group is reduced, it is necessary, to compensate for the resulting budget deficit, to increase it for another—or reduce the public services on which all depend. The currently proposed reform does not escape this mechanism: the new direct federal tax scales envisaged lighten the burden of some while increasing it for others; they relieve so-called modern families at the price of an additional burden for traditional families and single persons. One does not eliminate inequality; one shifts it. One does not resolve injustice; one changes its victims.

The conclusion that imposes itself is both sober and dizzying. The evolution of taxation is an eternal democratic battle, in which there is never a winner without a loser. What distinguishes one reform from another is not the abolition of injustice—for this is structurally impossible in a system of positive law—but the designation of the groups that benefit from it and those that bear its cost, as well as the magnitude of this transfer. The question that the people must decide is therefore not that of abstract justice, but that of acceptable compromise: does the overall gain justify the overall loss? And, more fundamentally still: will this reform be perceived as a unifying force—a step toward better-distributed solidarity—or as a segregating force, digging new fault lines between those who benefit from change and those who suffer from it?

9. Eternal and Unavoidable Injustice?

Are we then condemned to live in a tax system whose injustice is inherent, structural, irremediable? The answer, in our view, is no—but it calls for an important nuance.

This article has attempted to demonstrate that the debate on the taxation of spouses suffers from a flaw in perspective. The marriage penalty is dwelt upon as if it flowed from joint taxation as such, whereas it actually results from the absence of joint taxation of cohabiting partners. Individual taxation is demanded as a remedy to an inequality between spouses and cohabiting partners, without seeing that this same individual taxation creates a new inequality—that between couples and single persons.

“One seeks to correct an asymmetry by introducing another.”

This is not to claim that the current system is satisfactory. It is not. The gap between single-income and dual-income families remains insufficiently compensated. Fiscal federalism, by imposing joint taxation without harmonising relief mechanisms, produces considerable inter-cantonal disparities. The proposed reform, by this time imposing individual taxation without further framing social correctives, risks reproducing the same error in reverse.

These imperfections are not, however, a sign of failure. They are the inevitable consequence of a system that proceeds by successive approximations, by compromise between divergent interests, by legislative adjustments subject to the test of referendum. Tax law is, more than any other branch of law, a positivist work: it reflects less a universal truth than a collective choice, anchored in a given economic, social, and political context. What seemed just yesterday is not necessarily so today, and what is adopted today will inevitably be called into question tomorrow.

It is precisely here that the strength—and not the weakness—of our direct democracy lies. If legal philosophy cannot definitively resolve the question of tax justice, the democratic process allows us to approach it through iterations. Each vote is an adjustment, each legislative revision an attempt to better grasp the socio-economic reality of the moment.

“Tax law advances not in a straight line toward an abstract ideal, but by oscillations, by trial and error, by attempts and corrections.”

The upcoming vote on individual taxation does not escape this logic. It constitutes a step—forward or backward, the future will tell—on a path that has no final destination. But it is our step, arising from our collective choice, and consequently our responsibility to make it, as far as possible, the right one.