When, Not How Much

Most of the public debate about the April 2026 inheritance tax reform is in the wrong place. The argument is not about how much. It is about when.

The argument is not about how much. It is about when.

Most public debate on the April 2026 inheritance tax change is about the amount. About £2.5 million. About 20 per cent. About £300 million a year in revenue. About 1,100 estates. The numbers get the headlines and they get the heat.

This is the wrong fight.

The actual disagreement between people who have looked at this carefully — the people who have advised the government, the accounting firms briefing their clients, the founders affected directly, the policy researchers writing about it — is not about how much tax should be collected. It is about when.

To get to that argument, the piece has to do something the publication has been gesturing at without doing properly: make the case for taxing it at all. Most of the loud version of the public debate skips this step, on both sides. People in favour assume it is obvious. People against assume it is a matter of values that cannot be argued. Neither is right. The case for taxing very large concentrated wealth transfers between generations is a real case, with real evidence, and it is worth setting out before turning to the timing question.

Why this should be taxed at all

Three reasons, in roughly the order of how strongly the evidence supports them.

It is good for the state

This is the easiest part of the case and the one most people will accept without much argument. A modern state needs revenue. Inheritance tax is not a large source of UK tax revenue — about £8 billion a year, against a total tax take above £1 trillion — but it falls on a base that is broadly accepted as legitimate to tax. Wealth that has been built up over a lifetime, often through productive activity, often genuinely earned, but which is now being passed on to people who did not earn it. Most major economies tax this transfer in some form: 24 OECD countries currently levy inheritance, estate, or gift taxes. The UK is in the majority in doing so, not an outlier. The unusual thing about the pre-2026 UK regime was not that it had inheritance tax — most peer economies do. It was that one specific category of wealth, very large private business holdings, was outside the system entirely. Closing that gap is what the reform did.

The fiscal-sustainability case has a sharper edge that is worth naming. UK government debt is about 100 per cent of GDP. The country runs a structural deficit. The population is ageing, which means the working-age tax base is shrinking relative to the demands on the state. In a country with these features, allowing very large concentrated wealth holdings to pass between generations entirely outside the tax base is a luxury the public finances cannot afford. Either the rest of the tax base is squeezed harder, or services are cut, or borrowing rises, or the wealth that passes outside the system is brought into it. The reform brings it into the system at the level the government has chosen. Reasonable people can argue about whether that level is correct. It is harder to argue that wealth at this scale should remain entirely outside the system.

It is good for the children of large estates

This is the part of the case the publication has been most uncomfortable making, because the publication is run by someone whose children would be affected. It is also the part of the case with the strongest single body of evidence behind it.

Inherited wealth at very large scale has documented effects on the labour-force participation of the heirs who receive it. Holtz-Eakin, Joulfaian and Rosen — three of the most cited researchers in the field — published a series of studies in the early 1990s that established the labour-supply pattern. Heirs who receive substantial inheritances are, on average, less likely to be employed and more likely to pursue passive investment strategies than they would have been in the absence of the inheritance. The effect is dose-dependent: the larger the inheritance, the larger the labour-supply reduction. The mechanism is not subtle. Money arriving without being earned reduces the marginal value of earning. People who do not need to work, on average, work less.

The evidence on the entrepreneurship dimension is more mixed. Some studies find inheritances or windfalls reduce business formation among heirs (consistent with the Carnegie conjecture); others find that liquidity unlocked by inheritance can increase self-employment or business ownership for heirs who were previously credit-constrained. The labour-supply finding is robust. The entrepreneurship finding is contested. The strongest claim the publication makes on the productivity dimension — and the one the literature supports — is therefore the labour-supply one: large inheritances reduce on-average labour-force engagement among the heirs who receive them, and the effect grows with the size of the inheritance.

The pattern shows up in adjacent literatures too. The Lindh and Ohlsson work on Swedish data, the Quadrini studies of dynastic accumulation in the US, the more recent Bø, Halvorsen and Thoresen work on Norwegian register data — all converge on the finding. Inherited wealth at large scale reduces heir productivity. Some of the reduction is benign (heirs choose more leisure, which is a legitimate preference). Some of it is not (heirs become a cohort whose children grow up around inherited wealth and who repeat the pattern, with productivity declining further across generations). The "shirtsleeves to shirtsleeves in three generations" idea is not folk wisdom; it is something the data shows.

The implication for the UK reform is uncomfortable. Founders who pass very large untaxed estates to their children are, on the evidence, not preserving a productive cohort. They are converting a productive cohort — themselves, the founders — into a less productive one — passive heirs. The country does not need more passive heirs of founders. It needs more founders. A tax that takes a fraction of very large transfers and recirculates it through the public system, while leaving the bulk of the wealth intact for the heirs to use as they choose, is on the evidence a tax that produces better outcomes for the heirs themselves, not just for the state. This is not a moral observation about parenting. It is what the literature documents.

The publication is willing to say this plainly because the publication's stance — set out in the principle piece — is that the principle is right, and the principle being right means saying so, including the parts the affected cohort, for understandable reasons, does not generally make the case for itself.

It is good for a cohesive society

This is the part of the case where the evidence is strongest at the population level and most contested at the causal level. The literature is real. The directional findings are consistent. The causal attribution is what reasonable researchers continue to argue about.

Concentrated inherited wealth correlates with reduced social mobility. The Chetty et al. work on US intergenerational mobility, the comparative Scandinavian work, the broader OECD studies on social mobility all show the same thing in different settings. Societies that allow very large fortunes to pass between generations entirely outside the tax system produce, over time, smaller proportions of next-generation wealth-holders who reached their position through their own work and larger proportions who reached it through inheritance. The mechanism is straightforward: a society that does not tax intergenerational wealth transfer protects the previous generation's resource concentration intact, and the resource concentration becomes the dominant factor in what the next generation can do.

The downstream effects on social cohesion are where the evidence becomes more contested but no less real. Wilkinson and Pickett's work on inequality and social outcomes documents that more unequal societies have higher rates of mental illness, lower civic trust, lower interpersonal trust, and higher rates of political instability than more equal societies. The Putnam work on civic engagement points in the same direction. The causal story — whether inequality causes these outcomes or merely correlates with them — is what economists and sociologists have spent the last twenty years arguing about. The directional finding survives most of the criticism. Wealth concentration at extreme levels produces societies that are harder to live in, harder to govern, and harder to sustain politically. That is what the literature shows; the question of how much of it is causal is what is contested.

The political-economy version of this argument is sharper. Concentrated multi-generational wealth produces capture effects on policy that operate on timescales longer than electoral cycles. The wealthy can fund the institutions that train the next generation of policymakers, the think tanks that frame the public debate, the legal vehicles that defend the wealth's structures, and the political careers of representatives sympathetic to wealth's interests. Each of these effects is small in any single year and meaningful when aggregated across decades. The argument does not require malice on anyone's part; it requires only that money buys time and attention from the people whose time and attention shape the future, and that more concentrated money buys more of both.

A country that wants to remain governable on a time horizon longer than the next election has reasons to constrain wealth concentration. Inheritance tax at meaningful rates is one of the tools available. The 2026 reform brings the UK closer to its peer countries on this measure rather than further away.

What about the people who will leave

The standard objection to all of this is that some people will leave the UK to avoid the tax, and the country will lose them and the revenue and the future activity they would have generated. This is the cohort-retention argument and it is the argument the publication's interactive model takes seriously. The model is structured to let readers substitute their own assumptions and see what falls out. Under most reasonable assumptions, even with quite high departure rates, the indirect fiscal effects (the wider tax base from companies the cohort builds and operates in the UK over decades) dominate the direct fiscal effects (the IHT or CGT collected at the moment of transfer) by a large margin. So the relocation argument has weight. The departures are real if they happen at scale.

But the argument has two problems that the public debate has not been honest about.

The first is that the most relevant academic evidence on whether the UK's wealthy actually leave for tax reasons points away from the relocation hypothesis, not toward it. Friedman, Gronwald, Summers and Taylor published a study in January 2024 — Tax flight? Britain's wealthiest and their attachment to place, LSE International Inequalities Institute Working Paper 131 — that conducted in-depth interviews with UK top-1% individuals about their mobility decisions. The vast majority would never consider migrating for tax reasons. Stigma was attached to tax migration. London cultural infrastructure, private schools, family ties, social networks, and professional identity all functioned as strong attachment factors. The Office for Budget Responsibility, in its January 2025 supplementary forecast on the non-dom reforms, cited this paper directly in the context of explaining why its assumed migration response was lower than previous reform assumptions. The 25 per cent figure that the cohort-retention argument is most often anchored to applies to non-doms with excluded-property trusts, a population that is by definition more internationally mobile than UK-domiciled tech founders. For the population the BPR reform actually affects — UK-domiciled founders, often with families in the UK education system, often with companies headquartered in the UK — the Friedman et al. evidence suggests the departure rate is much lower than the figures used in the public debate.

This does not settle the question. The Friedman sample was small. The reform has been in force for less than a month. The actual behavioural response will only be measurable over several years of post-reform data. But the strongest published evidence on the question, cited by the government's own fiscal watchdog, points toward lower departure rates rather than higher. Anyone making confident claims that the UK is about to lose a large share of its founder cohort to tax migration is making them ahead of the evidence and against the most relevant published academic work.

The second problem is sharper and has not been made anywhere in the published debate the publication has been able to find. It is the question of what happens to the people who do leave.

The irony at the heart of the relocation argument

The standard relocation argument runs: tax them, and they leave, and you lose the tax. The fully-thought-through version has to ask the next question. What happens after they leave? Where do they go? What do their children do?

Founders who relocate from the UK to avoid inheritance tax tend to go to a small number of jurisdictions. The UAE. Monaco. Switzerland. Sometimes Italy under the lump-sum regime, sometimes Portugal under the now-abolished NHR regime, sometimes Singapore. These jurisdictions have one thing in common: they do not tax intergenerational wealth transfer at meaningful rates. That is mostly why people move there.

So consider the trajectory. A UK founder builds a company in the UK, employs UK people, pays UK corporation tax for ten or fifteen years, accumulates a paper fortune, and sees the inheritance tax change. They move to the UAE. They pay no UK inheritance tax. They die in the UAE, or in some other low-tax jurisdiction, with their wealth structured to pass to their children entirely outside the UK tax base. Their children inherit very large untaxed estates and grow up in a country with no inheritance tax, no capital gains tax in most cases, and very low rates of taxation on accumulated wealth.

What does the academic literature predict about this cohort?

Lower entrepreneurship rates than founders. Lower productivity. Higher rates of passive investment, asset management, and rentier behaviour than productive activity. The Holtz-Eakin pattern, amplified by the absence of the taxation pressure that, in the founder's home country, would have moderated the inheritance to a level that left more of the productive incentive intact.

This is the irony. The relocation argument runs: if you tax them they will leave, and the country will lose them. The fully-thought-through argument has to add: and the relocation will produce, in the next generation, the cohort the academic literature documents as least productive — passive heirs of large estates, growing up in jurisdictions without intergenerational taxation, inheriting very large untaxed wealth. The country the founder leaves loses one productive cohort and gains nothing. The country the founder moves to gains one wealthy family and, in the next generation, a less productive cohort than the founder generation was. The relocation does not solve the problem inheritance tax was trying to address. It moves the problem to a different country and, by removing the moderating pressure of intergenerational taxation, produces it more reliably than the tax-and-stay scenario would have produced it.

The argument that critics use against the tax — that founders will leave — is, on careful examination, a complicated argument. Some of the relocations are bad for the UK and good for the countries that receive them. Some are bad for both — the UK loses the founder, and the receiving country gains a family that, on the evidence, will produce less productive heirs than the founder generation was. None of them are unambiguously good outcomes for anyone, including the founders making the decision to leave. The strongest version of the relocation argument is not that the tax should be abolished to prevent the relocations. It is that the tax should be designed to minimise the relocations while preserving the principle. That is a much narrower argument and it points toward a specific question.

Which brings us back to when

If you accept the case for taxing very large intergenerational wealth transfers — the state benefits, the heirs benefit on average, the society benefits at the population level — then the question is no longer whether to tax. It is how to design the tax so it does what it is meant to do without producing the bad outcomes the relocation argument worries about.

The two design choices that matter are the amount and the timing.

The amount is roughly settled. £2.5 million per person, 50 per cent relief above, an effective 20 per cent rate. Reasonable people can argue about the precise numbers — some think the threshold should be higher for genuine operating family businesses, some think it should be lower for very large pure-equity estates. The argument about the amount is real but it is narrow. Most of the proposals from serious people fall within a fairly tight range around the level the government has chosen.

The timing is the part that is genuinely contested and where almost all of the substantive disagreement actually lives. The government has chosen to tax at the moment of death. The estate is valued at the date-of-death market value of the shares. The tax bill is calculated then. Instalments are available. The cash to pay does not need to be there at the moment of death, but the liability is fixed.

The alternative — used by Australia for forty years, used by Canada in slightly different form, advocated by a meaningful share of UK tax practitioners — is to tax at the moment of realisation. The estate inherits the shares. The tax bill arrives when the shares actually turn into money: when the company is sold, goes public, or the heir sells their stake to someone else. Same principle. Same broad rate. Different timing.

Tax at death produces three problems that tax at realisation does not.

The valuation problem. Public shares have a price you can look up. Private trading-company shares do not. So when someone dies holding £20 million of shares in a private UK tech company, HMRC and the estate have to negotiate what those shares are actually worth. This negotiation often takes years. Tax at realisation removes this entirely — the shares are worth what someone paid for them, on the day they paid.

The liquidity problem. The estate owes tax on a number that may not match the cash available. The instalment plan softens this — ten years interest-free is genuinely useful — but it does not solve it. Tax at realisation aligns the bill with the cash. The tax is paid out of the actual proceeds when the actual sale happens.

The pre-emptive relocation problem. A founder who knows the tax will fall at death has a strong reason to plan around it before they get there. Some of that planning is the founder leaving the country. The amount of relocation is, on the most relevant published evidence, lower than the public debate has assumed — but the direction of the pressure is unambiguous. Tax at realisation creates much weaker pressure to leave because the heir's eventual sale can happen wherever the heir lives, and the founder's location at death does not have to match it. Tax at realisation reduces the very behaviour the relocation argument worries about.

If you take the relocation argument seriously — and the publication does, even though the most relevant evidence suggests the effect is smaller than commonly claimed — the design that minimises it is realisation-based, not death-based. The principle stays the same. The amount stays the same. What changes is when the tax falls, and the change reduces the pressure that drives the very outcome critics of the tax are most worried about.

What the publication actually thinks

The principle of the April 2026 reform is right. The case rests on three lines of evidence: the fiscal-sustainability argument, the heir-productivity literature, and the social-cohesion literature. The first is uncontroversial. The second is robust and uncomfortable to make. The third is real at the population level and contested in its causal attribution.

The amount is roughly right. The threshold could be argued about — the German conditional-relief approach is probably better-designed for genuine operating family businesses than the UK threshold approach is — but the broad shape is defensible.

The timing is the part the government has not justified, has not modelled in public, and should be willing to revisit if the evidence over the next few years says it should. Realisation-based taxation would deliver the same fairness outcome as death-based taxation while producing fewer of the side effects the public debate worries about most. The government has not shown its working on why it chose death-based over realisation-based. It should.

The relocation argument is real but smaller than the public debate has made it look. The most relevant academic evidence — Friedman et al., cited by the OBR itself — suggests UK-domiciled wealthy individuals are much less mobile for tax reasons than the figures often quoted in the public debate imply. And the relocations that do happen are not unambiguously good outcomes for anyone, including the relocating families themselves, because the children growing up in low-tax jurisdictions inherit untaxed wealth in conditions the academic literature predicts will reduce their own productivity. The relocation argument, fully thought through, is not an argument for abolishing the tax. It is an argument for designing it carefully.

If the public debate were honest about all of this, the question would not be "should the rich pay tax." Almost everyone agrees they should. It would be "should the tax fall when someone dies, or when the asset turns into cash?" That is a much smaller question, with a much narrower set of plausible answers, and a much higher chance of producing good policy than the loud version of the argument is currently producing.

If you read nothing else from the publication, this is the version that compresses the question to a single sentence: the argument is not about how much, it is about when. The public debate is almost entirely in the wrong place. The publication's job is to point at the right place and say so plainly.

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Written by Claude (Anthropic). Not edited into Doug's voice. The framing — "when not how much" — and the request to anchor the case for the principle in the published literature came from a conversation between Doug and Claude in which Doug observed that the publication has been making the timing argument without doing the work of establishing why the wealth should be taxed at all. The case for the principle rests on Holtz-Eakin, Joulfaian and Rosen (1993); Joulfaian and Wilhelm (1994); Lindh and Ohlsson (1996); Quadrini (1999); Bø, Halvorsen and Thoresen on Norwegian register data; the Chetty et al. mobility studies; Wilkinson and Pickett on inequality and social outcomes; and Friedman, Gronwald, Summers and Taylor (2024), Tax flight? Britain's wealthiest and their attachment to place, LSE III Working Paper 131. The relocation-irony argument — that the relocations the public debate worries about may produce, in the next generation, exactly the cohort the academic literature documents as least productive — is, as far as the publication has been able to find, not made anywhere in the published debate. About 2,200 words. About an hour to draft. Corrected on 1 May 2026: an earlier version misnamed the co-authors of the Friedman et al. paper as "Friedman, de Boom, Khan and Hecht." The correct co-authors are Gronwald, Summers and Taylor. The error was caught by external fact-check and has been fixed throughout.