The Cross-Border Tax Guide to Selling a UK Business
Selling a UK limited company as a US citizen or dual filer triggers two overlapping tax systems. Understanding cross-border tax and UK business sale rules — Business Asset Disposal Relief, US capital gains tax, and the CFC dividend trap under §1248 — is essential before you sign a sale agreement, not after.
By the TaxYork Cross-Border Tax Team — reviewed by a US-UK dual-qualified adviser (CPA / Enrolled Agent).
How Much Tax Do You Pay When You Sell a Business in the UK?
A UK resident seller of a trading company typically pays Capital Gains Tax on the sale proceeds, with the tax reduced if Business Asset Disposal Relief applies. BADR cuts the rate on qualifying gains up to a lifetime cap of £1 million, though that rate is rising each year through 2026.
Business Asset Disposal Relief Rates for 2025–2026
BADR (formerly Entrepreneurs' Relief) has stepped up in stages. Disposals made on or before 5 April 2025 qualify for 10%; disposals between 6 April 2025 and 5 April 2026 attract 14%; and from 6 April 2026, the rate rises again to 18%, aligning it with the standard higher-rate CGT band for business disposals. Sellers outside BADR's £1 million cap, or without at least two years of qualifying ownership, pay the ordinary 18% or 24% rate instead.
Disposal date
BADR rate
Lifetime cap
On or before 5 April 2025
10%
£1,000,000
6 April 2025 – 5 April 2026
14%
£1,000,000
From 6 April 2026
18%
£1,000,000
Standard CGT (no relief)
18% basic / 24% higher
N/A
Where part of the purchase price is deferred as an earn-out, HMRC's installment rules under TCGA s.280 can spread CGT payment over up to eight years — but only where consideration is genuinely deferred cash, not loan notes or debentures.
Timing and the Two-Year Ownership Test
BADR is not available on demand. Sellers must have held at least 5% of the company's ordinary share capital and voting rights, and been an officer or employee, for a continuous two-year period ending on the date of sale. Selling early to lock in a lower headline rate can backfire if the two-year clock has not run, pushing the entire gain into the standard 18% or 24% band with no relief at all.
Do I Have to Pay US Tax If I Sell My UK Business?
Yes. The United States taxes citizens and green card holders on worldwide gains, so a UK share sale is reportable on the US return regardless of where the company or the seller lives. The gain is taxed at federal long-term capital gains rates if the shares were held over a year, plus the 3.8% Net Investment Income Tax on top.
US Long-Term Capital Gains Brackets
The bracket that applies depends on the total taxable income for the year of sale, and the thresholds shift each year due to inflation.
Filing status
0% rate
15% rate
20% rate
Single (2025)
Up to $48,350
$48,351–$533,400
Above $533,400
Single (2026)
Up to $49,450
$49,451–$545,500
Above $545,500
Married filing jointly (2025)
Up to $96,700
$96,701–$600,050
Above $600,050
Married filing jointly (2026)
Up to $98,900
$98,901–$613,700
Above $613,700
These figures come from the IRS's own 2026 inflation adjustment release. NIIT applies once MAGI exceeds $200,000 for a single filer or $250,000 for married filers filing jointly, and, unlike US federal tax, it generally cannot be reduced by UK tax credits — a point most sellers only discover at filing time. Our guide to the Net Investment Income Tax covers this gap in detail.
Short-Term Versus Long-Term Treatment
The preferential 0%, 15%, and 20% US rates only apply if the shares were held for more than one year before the sale closed. A company sold within twelve months of incorporation, or of a US owner's share purchase, is taxed at ordinary federal rates up to 37% instead — a gap worth planning around if a sale date is flexible.
What Makes Cross-Border Tax Selling a UK Business So Complicated for US Owners?
The complication most advisers miss is that a UK limited company majority-owned by US persons is a Controlled Foreign Corporation under US law. That single classification changes how the sale gain is taxed and is the reason cross-border tax planning for selling a UK business has to start years before a buyer ever appears.
The CFC Trigger
Under the CFC definition in §957, a foreign company becomes a CFC when US persons collectively own more than 50% of its vote or value. Any US person owning 10% or more is then a "US shareholder" subject to Subpart F and GILTI while the company is held, and to a special recharacterization rule the moment it is sold.
No QSBS Relief for a UK Company
American founders selling a US start-up sometimes shelter almost all of their gains under the Qualified Small Business Stock rules in §1202, which can exclude millions of dollars of gain from federal tax. That relief requires a domestic US C-corporation at issuance and throughout the holding period, so a UK limited company can never qualify, even if a US holding company is inserted above it later, because a domestic corporation never issued the underlying stock. Sellers comparing notes with US-only founders should expect a meaningfully higher federal tax bill on the same size of gain for that reason alone.
How Does the CFC Dividend Trap Under §1248 Work?
When a US shareholder who has held 10% or more of the CFC stock sells the stock, §1248 recharacterizes some or all of the gain as a dividend, up to the company's accumulated earnings and profits, rather than as a straightforward capital gain; this is the practitioner-grade trap that most articles on cross-border tax selling a UK business never mention.
Why the Recharacterization Matters
§1248(b) caps the individual's rate at the long-term capital gains rate for stock held for over a year, so the rate itself often remains similar. The real cost is mechanical: the recharacterized portion becomes a dividend for Foreign Tax Credit purposes, and UK CGT paid on the sale may sit in a different FTC "basket" than the credit is needed in. Because BADR's rate (14–18%) is already lower than the US LTCG rate it is meant to offset, this basket mismatch can leave a real slice of the gain taxed twice, with no credit left to absorb it.
Can I Avoid Double Taxation When Selling a UK Company as a US Citizen?
Partial relief is available through the Foreign Tax Credit, but full relief is rare once §1248 and NIIT are both in play. Form 1116 lets you claim UK CGT paid against US tax on the same income, but credits cannot cross baskets, and NIIT sits outside the FTC system entirely.
Planning Before the Sale
Owners who anticipated the CFC classification early sometimes reduce the pre-sale drag with a §962 election, which allows an individual US shareholder to be taxed on Subpart F and GILTI at roughly the corporate-equivalent rate rather than ordinary rates up to 37%. This is a running-the-business decision, not a sale-year fix, which is exactly why cross-border tax andbusiness-planning UK business planning needs to begin well before heads of terms are signed. Sellers who are also behind on filing for the business's foreign accounts can often catch up through the same streamlined mechanism used for sellers of UK homes who fell behind on US filing.
What Reporting Comes With Owning and Selling a UK Company?
Every year, if a US person is a 10%+ shareholder in the CFC, Form 5471 is due with the US return — the penalty for a missed year is $10,000 per form, and the statute of limitations does not start until it is filed. If the seller ever contributed cash or property to the company, Form 926 may also have been required at the time of the contribution.
FBAR and Form 8938 for the Company's Accounts
Beyond Form 5471, US shareholders with signatory authority over the company's UK bank accounts may separately need to report those accounts on the FBAR and, above the relevant thresholds, on Form 8938. Both filings carry their own penalty regime, distinct from Form 5471, so a clean pre-sale review needs to check all three, not just the corporate return.
Cleaning Up Before Completion
Buyers' lawyers increasingly ask about the seller's US filing history during due diligence, so gaps in Form 5471 or FBAR compliance are best fixed before the sale closes, not after. Our article on FBAR and streamlined catch-up when moving to the UK explains the mechanism most sellers use to get current without penalty.
Case Study: Selling a UK Consultancy as a Dual Citizen
Consider "Anna," a US-UK dual citizen who built a London consultancy over eleven years and sold it for £2,000,000 in 2026. In the UK, £1,000,000 of gain qualified for BADR at 18%, and the remainder was taxed at the standard 24% rate — a UK bill of roughly £420,000. Because Anna held more than 10% of a CFC, §1248 recharacterized a portion of her gain as a dividend up to the company's retained earnings, and her US preparer had to split the Foreign Tax Credit across two baskets. On her US return, roughly $180,000 of the recharacterized §1248 dividend fell into a different Foreign Tax Credit basket than most of her UK tax credit, leaving around $40,000 of gain effectively taxed twice even before NIIT of close to $76,000 was added on top.
After NIIT, which the UK tax paid could not offset, Anna's total effective rate landed several points above either country's headline rate alone — precisely the outcome that early cross-border tax selling of a UK business, including a §962 election in the years before the sale, would have softened. She also had two years of unfiled Form 5471s cleaned up through streamlined procedures before completion, a step her buyer's counsel specifically requested. Anna's SIPP, built up alongside the company, will now be reviewed separately — a topic we cover in planning for a UK pension as a dual filer.
Get Cross-Border Tax Guidance Before You Sign a Sale Agreement
If you are weighing an offer for a UK company and hold US citizenship, green card status, or dual nationality, get advice before heads of terms are signed — the CFC and §1248 exposure is far easier to manage in advance than to unwind afterward. TaxYork's Cross-Border Tax Team models the UK and US numbers together, checks your Form 5471 history, and builds a sales-year estimated tax plan alongside the transaction, drawing on the same approach we set out in our guide to estimated US tax payments for dual filers. Email hello@taxyork.com, call 020 3488 8606, or visit taxyork.com to talk through your sale before you sign anything. For owners weighing a business exit alongside other UK assets, our Cross-Border Tax Guide to Inheriting UK Wealth covers the parallel planning questions.