The 60-day CGT return is a standalone Capital Gains Tax return that a non-UK resident must file — and pay any tax on — within 60 days of the completion date of a disposal of UK land. Unlike a UK resident, who only files this return when residential property produces an actual CGT liability, a non-resident must report every disposal of UK land: residential, commercial, mixed-use, and indirect disposals of property-rich companies. No tax due is not an exemption. A loss is not an exemption. Silence for 60 days is a £100 penalty on day 61.
For American citizens and Green Card holders who own UK property, the 60-day deadline is only the first of two filings. The same sale eventually reaches a US Form 1040 with a different cost basis, a different currency, a different set of reliefs and — if the property carried a sterling mortgage — a second, entirely separate taxable gain that has nothing to do with the house. This guide covers the UK filing in full, then the American layer that decides what the sale actually costs you.
What the 60-day CGT return is, and how it differs from Self Assessment
The return is filed through HMRC's dedicated "Capital Gains Tax on UK property" service, which sits outside the Self Assessment system entirely. It has its own account, its own reference number, its own deadline and its own payment. Filing a Self Assessment return later in the year does not discharge the obligation, and filing the 60-day return does not discharge Self Assessment if you are otherwise within it.
The regime began on 6 April 2015 for non-resident disposals of UK residential property, widened on 6 April 2019 to cover all UK land plus indirect disposals, and the reporting window moved from 30 days to 60 days for completions on or after 27 October 2021. HMRC's guidance on Capital Gains Tax for non-residents confirms the 60-day rule and the requirement to report even where no tax is payable.
The practical consequence is that the deadline arrives while you are still dealing with removals, currency transfers and a solicitor's completion statement. Sixty days sounds generous. It is not, once a valuation is needed.
Which disposals a non-resident must report
This is the single most misunderstood point, because the rule for non-residents is far wider than the rule for UK residents. A UK resident files the 60-day return only where a residential disposal generates CGT to pay. A non-resident files for every disposal of UK land, full stop.
That includes disposals where private residence relief wipes out the whole gain, disposals at a loss, disposals of a commercial unit, and disposals of shares in a company that derives most of its value from UK land.
- Residential property — houses, flats, and land with residential planning permission.
- Non-residential property — offices, shops, warehouses, farmland, and bare land.
- Mixed-use property — a shop with a flat above it, apportioned between the two.
- Indirect disposals — an interest in an asset that derives 75% or more of its gross value from UK land, where you hold (with connected persons) at least a 25% interest.
- Disposals producing no gain, no tax, or an allowable loss — all still reportable within 60 days.
The 60-day clock starts at completion, not exchange
The countdown runs from the completion date — the day the transaction is finalised and the keys change hands — not from exchange of contracts. That matters because a long gap between exchange and completion is common in UK conveyancing, and clients frequently start the clock in the wrong place and lose weeks.
The disposal date for calculating the gain, however, is normally the exchange date. So a sale that exchanges in March and completes in May falls into the 2025/26 tax year for computation purposes while its 60-day deadline runs from the May completion. Getting these two dates the wrong way round is one of the most common errors we correct.
Gifts and transfers into trust are disposals too, at market value, with the same 60-day clock — a point that catches American parents transferring a UK buy-to-let to an adult child.
How the gain is calculated: three methods, one default
Non-residents are not simply taxed on the whole increase in value since purchase. Because the regime only began in 2015 (and 2019 for commercial property), the legislation rebases the property so that only post-commencement growth is taxed by default.
HMRC's guidance on calculating the taxable gain or loss sets out three permitted methods. The default for residential property held before 6 April 2015 is rebasing to the market value on that date.
- Rebasing — use the market value at 5 April 2015 (residential) or 5 April 2019 (non-residential and indirect disposals) as the cost. This is the default.
- Straight-line time apportionment — compute the whole gain from original purchase to sale, then tax only the fraction of the ownership period falling after the rebasing date.
- Whole period of ownership — compute the gain from original acquisition with no apportionment. Usually elected only to establish a larger allowable loss.
- Mixed-use property splits: the residential element rebases to 5 April 2015, the non-residential element to 5 April 2019.
The rebasing valuation is where the money is won or lost
A retrospective valuation of what a property was worth on 5 April 2015 is not a formality. It is the single number that decides the size of the taxable gain, and for a London flat bought in 2006 it can easily swing the liability by tens of thousands of pounds.
HMRC can and does challenge weak valuations. An estate agent's one-line email is a weak valuation. A written report from a RICS-qualified surveyor, prepared on a red-book basis, referencing comparable transactions around April 2015, is a defensible one. If you are approaching a sale, commission the valuation before you complete rather than in a scramble afterwards.
Note the interaction with improvement costs: if you rebase to 5 April 2015, you can only deduct enhancement expenditure incurred after that date, because pre-2015 improvements are already reflected in the 2015 market value. Clients frequently try to deduct a 2011 extension on top of a 2015 valuation. That is double counting, and HMRC will find it.
Rates, allowances and the 2026/27 numbers
Capital Gains Tax on UK residential property is charged at 18% to the extent the gain falls within your remaining basic rate band and 24% above it. Since 30 October 2024, non-residential property has been charged at the same 18% and 24% rates, so the old distinction between property types no longer changes the rate — only the rebasing date.
The annual exempt amount is £3,000 for 2026/27. Non-residents are entitled to it in the normal way. Because a standalone 60-day return has no visibility of your other income for the year, you must estimate how much of your basic rate band remains when deciding how much of the gain is taxed at 18% and how much at 24%. HMRC accepts a reasonable estimate at the 60-day stage; the final position is corrected later.
You can model the numbers, including all three computation methods, in our UK non-resident CGT property calculator.
Private residence relief and the 90-day occupancy test
Americans who lived in the property before moving abroad often assume private residence relief (PRR) will shelter the gain. It may — but only partly, and only if they meet a test designed specifically to restrict non-residents.
For a tax year in which you are not UK resident, the property can only qualify as your residence if you or your spouse or civil partner spent at least 90 midnights in it (or in another of your UK dwellings) during that tax year. Nights do not need to be consecutive. If you fail the 90-day test for a year, that year is not a period of PRR occupation, and the relief is reduced proportionately.
The relief is apportioned across the period of ownership measured from the rebasing date where you rebase, plus the final nine months of ownership which qualify automatically if the property was your only or main residence at some point. Getting the fraction right, with a 90-day test applied year by year, is where most self-prepared 60-day returns go wrong.
How to actually file it from abroad
You need a "Capital Gains Tax on UK property" account, created through Government Gateway. This is a separate account from your Self Assessment account and requires its own identity verification — which is precisely where overseas sellers get stuck, because the standard verification routes lean on UK credit records, a UK passport or a UK driving licence.
Build in time for this. An American with no UK credit footprint can spend two weeks getting through identity checks, inside a 60-day window. Where online verification fails entirely, HMRC will issue a paper return on request, but the paper route is slow and the deadline does not move to accommodate it.
If an accountant files for you, you must first create the account yourself and then generate a reference number to authorise them. The agent cannot create the account on your behalf. This ordering trips up a large share of first-time non-resident sellers.
Penalties and interest if you miss the deadline
The penalties are automatic and they escalate. A late 60-day return attracts an immediate £100 fixed penalty. If the return is more than three months late, HMRC may charge daily penalties of £10 per day for up to 90 days. At six months a further penalty of £300 or 5% of the tax due — whichever is greater — applies, and the same again at twelve months. Deliberate withholding of information can push penalties far higher.
Late payment of the tax carries interest from the 60-day due date, and late payment penalties on top. HMRC's interest rate for late payments has been 7.75% since 9 January 2026, so a deferred £40,000 liability is accruing roughly £3,100 a year before penalties.
There is a reasonable excuse defence, and it is worth pursuing where identity verification genuinely failed despite prompt effort — keep the timestamps and correspondence. "I did not know the return existed" is not, on its own, a reasonable excuse.
The Self Assessment reconciliation nobody expects
If you are also within Self Assessment for the year — because you have UK rental income, for example — the disposal must be reported again on the capital gains pages of the tax return. The 60-day payment is then credited against the final liability.
This is where estimates get trued up. If you estimated your remaining basic rate band conservatively and paid at 24% throughout, the Self Assessment return may generate a repayment. If you were optimistic, there will be more to pay by 31 January.
Non-residents with UK rental profits should read this alongside our guide to US rental income for UK property owners, because the two filings share a set of figures and inconsistencies between them are exactly what triggers HMRC enquiries.
The US layer: what the IRS does with the same sale
Here is the part almost no UK-focused article covers. A US citizen or Green Card holder is taxed by the IRS on worldwide gains, so the same disposal appears on a Form 1040 — and the American computation shares almost nothing with the British one.
The IRS gives you no rebasing to 2015. Your US basis is the original purchase price, translated into dollars at the exchange rate on the date of purchase, plus improvements translated at their own historic rates. Your proceeds are translated at the rate on the completion date. A property that produces a modest UK gain after rebasing can produce a very large US gain, purely because sterling and the dollar have moved.
The section 121 exclusion — $250,000 of gain for a single filer, $500,000 for a married couple filing jointly — is available on a foreign home in the same way as a US one, provided you owned and used the property as your main home for at least two of the five years before the sale, as set out by the IRS in Publication 523. Long-term capital gain rates then apply, plus the 3.8% net investment income tax where thresholds are exceeded.
UK CGT actually paid is creditable against the US tax on the same gain via the foreign tax credit on Form 1116, in the passive category. The 60-day payment is generally helpful here: because the UK tax is paid promptly rather than at the following 31 January, the timing mismatch between the UK tax year and the US calendar year is smaller than it is for income.
The mortgage foreign-exchange gain: the second American bill
The sharpest trap in the whole transaction has nothing to do with the house. If the property carried a sterling mortgage, the IRS treats that debt as a separate financial instrument under section 988. Repaying it is a taxable event.
You borrowed pounds when the pound was worth one dollar amount and repaid them when it was worth another. If sterling weakened against the dollar over the life of the loan, it cost you fewer dollars to discharge the debt than you originally received, and the IRS treats that difference as ordinary income — taxed at your marginal rate, not at capital gains rates, and not sheltered by the section 121 exclusion.
The asymmetry is brutal: a currency gain on a personal-residence mortgage is taxable, while an equivalent currency loss is a non-deductible personal loss. Worse, every remortgage or product transfer that legally discharges and replaces the old loan is its own section 988 event, so clients who refinanced repeatedly through the low-rate years may have unreported gains sitting in several closed years. Our guide to selling a UK home as a US citizen works through the mechanics.
A worked example: a London flat sold in 2026
An American couple, non-UK resident since 2022, sell a London flat in September 2026 for £950,000. They bought it in 2009 for £480,000. The RICS valuation at 5 April 2015 is £790,000. They spent £40,000 on a kitchen and bathroom refit in 2018, and selling costs are £19,000.
Using the default rebasing method, the gain is £950,000 less £790,000 less £40,000 less £19,000 = £101,000. Split equally between two owners, that is £50,500 each, less the £3,000 annual exempt amount, leaving £47,500 each. With no other UK income, part of each gain falls in the remaining basic rate band at 18% and the balance at 24%. Two separate 60-day returns are due — the obligation is personal, not per property.
On the US side there is no rebasing. Their dollar basis is the 2009 purchase price at the 2009 rate — a period when sterling was far stronger — so the dollar gain is materially different from the sterling one, and the section 121 exclusion only helps if the two-out-of-five-years use test is still met after four years away. It generally is not. The UK CGT paid becomes a Form 1116 credit; whether it fully absorbs the US liability depends on the currency movement, not on the maths either country did in isolation.
What to do in the 60 days
Treat the deadline as a project that begins at exchange, not at completion. Create the HMRC account first, because identity verification is the one step you cannot compress. Commission the 5 April 2015 valuation next, because a surveyor's diary is the second thing you cannot compress. Everything else is arithmetic.
And run the American computation at the same time, not the following April. The difference between a well-sequenced disposal and a rushed one is rarely the UK tax — it is the US tax on a currency movement nobody modelled and a mortgage nobody thought was a taxable asset.
TaxStone prepares 60-day CGT returns alongside the US reporting for the same disposal, so the two computations are reconciled once rather than argued about twice. If you have a UK sale in progress or completed in the last few weeks, contact us with the completion date and we will tell you where the deadline falls.
