The US Exit Tax: What Wealthy US-UK Clients Should Know

The US Exit Tax: What Wealthy US-UK Clients Should Know

The US exit tax is a one-off charge that can be levied on wealthy Americans and long-term green card holders who give up their US status while living in Britain. It treats you as if you had sold everything you own the day before you leave, then taxes the gain. This guide explains what it is, who it catches, and how the sum is worked out.

What exactly is the US exit tax?

When a US citizen renounces their passport, or a long-term resident returns a green card, the United States requires a final settlement before allowing the tax relationship to end. That settlement is governed by Section 877A of the Internal Revenue Code, which Congress introduced in 2008 to replace an older, easier-to-dodge regime. The US exit tax is not a fee for leaving; it is an income tax on the built-up gains in your worldwide assets, triggered by the act of expatriation.

The mechanism is a deemed sale, sometimes called mark-to-market. On the day before you expatriate, the Internal Revenue Service pretends you sold every asset you hold — your investment portfolio, your London flat, your stake in a private company, your crypto — at fair market value. The paper profit becomes a real, taxable gain, even though you have not sold anything and still own all of it the next morning. The IRS expatriation tax overview sets out the framework, and the fine details are in the instructions for Form 8854.

Timing hinges on your expatriation date, which is a specific, legally fixed moment rather than a gradual process. For a citizen, it is usually the day you appear before a consular officer and formally renounce; for a green-card holder,r it is the day you file the abandonment paperwork or when a court or administrative order becomes final. That single date fixes the valuation of your whole estate, so a swing in markets or a large transaction in the days either side can materially change the bill. This is why advisers rarely treat expatriation as a spur-of-the-moment decision — the calendar itself is a planning tool.

Two points catch British-resident clients off guard. First, the charge only applies if you are a covered expatriate — most ordinary earners escape it entirely. Second, walking away from your US status does nothing to your UK position: if you remain UK tax resident, HMRC still expects its share, and the two systems must be reconciled carefully. Our note on renouncing US citizenship looks at the strategic side; this piece stays on the mechanics.

Who has to pay it — the covered expatriate test

You only face the US exit tax if you are both an expatriate and a covered expatriate. The first label is easy to earn. You become an expatriate the moment you renounce your citizenship at a US embassy, or when a green card holder who held their card for at least 8 of the last 15 tax years abandons it. That eight-year rule is why long-settled residents in the UK are frequently in scope without realizing it — a detail we cover in our guide to green-card abandonment and the IRS rules for departing green-card holders.

The second label is where the money is. You are a covered expatriate if you meet any one of three tests. Meeting a single test is enough; you do not need to fail all three.

The three covered expatriate tests

The net-worth figure is fixed and, unlike the others, is not adjusted for inflation, so asset growth quietly pushes more people over it each year. The income-tax threshold is indexed — it was $206,000 for 2025, confirmed in the Form 8854 materials, and rises annually. The third test is the cruelest: a wealthy client with immaculate finances but a couple of unfiled years is covered solely due to a paperwork failure, which is why our covered-expatriate testing guide stresses cleaning up filings first.

Who is let off

Two narrow exceptions can spare you covered status even if you cross a threshold. Certain dual citizens from birth — people who were citizens of both the US and another country at birth and still hold and are taxed by that other country — may be exempt, as may individuals who expatriate before age 18½. Both carve-outs still require a certified compliance history on Form 8854, so the paperwork is unavoidable. Many so-called accidental Americans assume they qualify automatically; in practice, the conditions are strict.

How the charge is calculated

Once you are a covered expatriate, the US exit tax is built in stages, and different asset classes are treated in very different ways.

The deemed sale of your general assets, including shares, money, real estate, and business interests, is the main feature. You add up the net unrealized gain across the whole portfolio, then subtract the exclusion amount, which was $890,000 for 2025 and is indexed each year. Only the gain above that exclusion is taxed, and it is taxed at the capital-gains rates that would have applied to a genuine sale. So a covered expatriate sitting on $1.4 million of unrealized gain would, broadly, be taxed on roughly $510,000 after the exclusion.

Other assets sit outside the deemed sale and follow their own rules:

• Eligible deferred compensation — such as certain pensions from a US payer who agrees to withhold — is generally left alone at exit. Still, future payments suffer a flat 30% withholding when they are eventually paid.
• Ineligible deferred compensation is treated as if the whole amount were paid to you the day before expatriation and taxed at once.
• Specified tax-deferred accounts, including IRAs, are deemed fully distributed the day before you leave — the entire balance becomes taxable income, though no early-withdrawal penalty applies.
• Interests in non-grantor trusts are subject to 30% withholding on the taxable portion of distributions, rather than an upfront charge.

There is one relief worth knowing about. For the general deemed-sale gains — though not for the deferred accounts — you can elect to defer payment of the tax until you actually sell each asset, provided you post adequate security, such as a bond, and formally waive treaty protections that might otherwise block collection. Interest accrues over the deferral period, so it is a cash-flow tool rather than a savings tool. Still, for an illiquid estate dominated by a private business, it can prevent a forced sale simply to fund the exit charge.

None of this happens in a vacuum on the British side. If you remain a UK resident, the same assets sit inside HMRC’s net too. The UK does not recognize the US deemed sale — so you can end up taxed by one country on a fictional disposal and by the other only on a later real one, with the timing mismatch making foreign tax credits hard to line up. Coordinating the US exit tax with your UK capital-gains position, and deciding whether to crystallize or hold particular assets, is where most of the real value of advice lies.

You report the full calculation on Form 8854, which is filed with your final dual-status income tax return for the year of expatriation. Our walkthrough of Form 8854 covers the sequencing because filing the return without the statement, or vice versa, can itself trip the compliance test. The full statutory language, for advisers who want it, is in 26 U.S.C. § 877A.

An illustrative example

Take Priya, a fictional composite. She is a US citizen who has lived in London for two decades, running a music-licensing business. Her net worth is about $3.2 million, so she clears the first test and is a covered expatriate. Upon renouncing, her share portfolio and business stake carry $1.5 million in unrealized gains; after the $890,000 exclusion, roughly $610,000 is taxed at capital-gains rates. Separately, her US IRA of $400,000 is deemed distributed in full and taxed as ordinary income. Priya still owns every asset the day after — but she has a substantial US tax bill, and because she remains a UK resident, she must also check how each element interacts with HMRC’s rules before she signs anything.

The sting in the tail: gifts and bequests

The US exit tax is not always the end of the story. Under Section 2801, any US citizen or resident who later receives a gift or inheritance from a covered expatriate may be subject to a separate transfer tax at the top gift-and-estate rate of 40%. The liability falls on the recipient, not the person who left — so a covered expatriate’s US-based children can inherit a tax problem years after the expatriation itself. For families split across the Atlantic, this often matters more than the exit charge, and it is a reason to model the whole picture before renouncing rather than after.

Talk to Jungle Tax before you file.

The US exit tax rewards planning and punishes improvisation. If you are weighing up renouncing your citizenship or handing back your green card, get the numbers modeled before you book the embassy appointment. Our cross-border team works together on the US and UK sides so nothing is missed.

Email hello@jungletax.co.uk, call 0333 880 7974, or visit jungletax.co.uk to arrange a consultation.