Which Form 8949 box do I check for shares sold through a UK broker?

Because a UK broker does not issue Form 1099-B, use box C in Part I for sales of shares held one year or less and box F in Part II for shares held more than one year. Holding period runs from the day after the trade date of purchase up to and including the sale date. Boxes I and L are reserved for digital assets and should not be used for ordinary UK listed shares.

Can I use my HMRC capital gains figures on my US return?

Not directly. HMRC figures are in sterling and use UK share matching, including the section 104 average cost pool and the 30-day rule. The US requires each lot's cost translated at the purchase date rate, proceeds at the sale date rate, and specific identification or first-in, first-out matching. The UK return is a useful source of trade data, but the US computation has to be rebuilt separately.

Can a UK gain be a loss on my US tax return?

Yes. If sterling weakened against the dollar between purchase and sale, the dollar value of your proceeds can fall below your dollar cost even though the sale produced a sterling gain. The reverse also happens: a UK loss can become a US gain if sterling strengthened. This is why US gains must be calculated in dollars at each transaction date rather than by converting the UK gain.

Is UK stamp duty on share purchases part of US cost basis?

IRS instructions describe basis as the purchase price plus costs of purchase such as commissions. Stamp Duty Reserve Tax, usually 0.5% on electronic purchases of UK shares, is paid to acquire the shares, so in our practice it is added to US basis together with the dealing charge, translated at the purchase date rate. GOV.UK also lists SDRT paid on purchase as a deductible cost for UK gains.

Can I claim UK Capital Gains Tax as a US foreign tax credit?

Usually, if you live in the UK. IRS Publication 514 treats a US citizen with a foreign tax home as a nonresident for a sale of personal property, making the gain foreign source, only if foreign tax of at least 10% of the gain is paid. Gains covered by the UK annual exempt amount may fail that test. Credits are limited on Form 1116, with unused UK tax carried back one year or forward ten.

How many years of missed US tax returns must I file for UK share sales?

Under the Streamlined Foreign Offshore Procedures, a non-willful US person living abroad files the three most recent years of returns whose due dates have passed and six years of FBARs, with no penalty. Earlier share sales still need reconstructing where they affect capital loss carryovers or which purchase lots remain for later sales under first-in, first-out matching.

Missed US Tax Returns: UK Share Sales, No Form 1099-B

Missed US tax returns that include sales of UK-listed shares are fixable: you report every disposal on Form 8949 yourself, using box C for short-term sales and box F for long-term sales because a UK broker issues no Form 1099-B, with proceeds and cost each converted to US dollars at the rate on the date of that transaction. The totals flow to Schedule D, UK Capital Gains Tax paid can usually be claimed on Form 1116, and a non-willful filer living in the UK can normally bring the years up to date through the Streamlined Foreign Offshore Procedures without penalty.

UK share sales are where catch-up filings most often go wrong: the UK gain you reported to HMRC is rarely the US gain, and HMRC's cost method is not one the IRS accepts for ordinary shares. In the returns we prepare for investors and business owners with UK brokerage accounts, rebuilding share disposals is usually the largest single task in a multi-year catch-up.

Why do missed US tax returns with UK share sales need special handling?

A US citizen or green card holder is taxed on worldwide income, so a sale of shares in a FTSE company through a UK platform is reportable on the US return exactly as a sale through a US broker would be. The difference is the paperwork. A US broker sends both you and the IRS a Form 1099-B showing proceeds and, for most shares bought in recent years, cost basis. A UK broker sends neither. You receive contract notes for each trade and an annual or tax-year statement, all in sterling, built around UK tax rules.

That creates three problems. First, every number on Form 8949 must come from your own reconstruction and be supportable from records. Second, every sterling amount must be translated into dollars at the right date, which changes the size of the gain and sometimes its direction. Third, UK rules for identifying which shares were sold, including the section 104 pool and the 30-day rule, differ from the US rules, so the UK capital gains pages you filed with HMRC cannot simply be copied across.

Missed US tax returns are also rarely just about shares: the same account is reportable for FBAR purposes, its dividends are income, and UK funds raise separate PFIC issues outside this article.

Which Form 8949 box applies when no Form 1099-B is received?

Form 8949 is the IRS form on which individual sales of capital assets are listed before being totalled on Schedule D. Its boxes tell the IRS whether a sale was reported to it on an information return. The current instructions at https://www.irs.gov/instructions/i8949 are explicit: short-term transactions for which you did not receive a Form 1099-B or Form 1099-DA go in Part I with box C checked, and long-term transactions without a Form 1099-B or Form 1099-DA go in Part II with box F checked. Boxes I and L are the digital asset equivalents and are not used for ordinary UK shares.

Short-term or long-term depends on the holding period. The instructions say to begin counting on the day after you acquired the property and to include the day you disposed of it; a holding period of more than one year is long-term. Use trade dates, not the settlement dates also shown on UK contract notes.

How do you complete each Form 8949 column for a UK sale?

The columns are labelled (a) to (h) and each one has a specific meaning for a UK disposal. Working through them in order is the simplest way to avoid gaps:

Column (a), description of property: the number of shares and the company, for example 40,000 shares of a named UK plc.
Column (b), date acquired: the trade date of the purchase lot you are treating as sold.
Column (c), date sold or disposed of: the trade date of the sale.
Column (d), proceeds: because no Form 1099-B was received, the instructions say to enter net proceeds, meaning gross proceeds minus selling expenses such as the broker's commission on the sale, translated into dollars.
Column (e), cost or other basis: the purchase price plus costs of purchase such as commissions, translated into dollars at the purchase date, and adjusted for any corporate actions.
Column (f), code: left blank for most UK sales. Code W is used for a nondeductible wash sale loss, and code M where several transactions are summarised on one row with a supporting statement. Code E is not the right code for selling costs here, because it applies only when a Form 1099-B or similar statement was received; without one, selling costs are simply netted in column (d).
Column (g), adjustment: the amount of any adjustment explained by the code in column (f), such as the disallowed part of a wash sale loss, entered as a positive number.
Column (h), gain or loss: column (d) minus column (e), combined with any column (g) adjustment.

Which exchange rate should you use for UK share proceeds and cost?

The IRS page on foreign currency at https://www.irs.gov/individuals/international-taxpayers/foreign-currency-and-currency-exchange-rates states that amounts on a US return must be expressed in US dollars and that you should use the exchange rate prevailing when you receive, pay or accrue the item. For a share disposal that means two separate translations: the cost is translated at the rate on the purchase date, and the proceeds at the rate on the sale date. Purchase costs such as commissions and stamp duty follow the purchase date; selling costs follow the sale date.

The page lists government and commercial rate sources and links to yearly averages, but a share sale happens on a single day, so in our practice we use the daily rate for each trade date, from one documented source applied consistently. Converting the net sterling gain at a single rate, the most common self-prepared shortcut, ignores the fact that the dollar cost was fixed on the purchase date.

Why can the US gain differ from the UK gain, or even reverse?

Because the US measures the gain in dollars and the UK measures it in sterling, movements in the pound between purchase and sale change the US result without affecting the UK one. If sterling weakened against the dollar while you held the shares, the dollar value of your proceeds is lower relative to your dollar cost, and a modest UK gain can become a US loss. If sterling strengthened, the US gain is larger than the UK gain, and a UK loss can become a US gain on which US tax is due even though HMRC treats the same sale as a loss.

A UK loss that becomes a US gain produces US tax with no UK tax to credit against it; a UK gain that becomes a US loss means UK tax was paid on income producing no US tax, which limits the usable credit.

Can you use the UK section 104 pool for US cost basis?

No. HMRC's helpsheet HS284 sets out the UK matching order for shares of the same class in the same company: shares acquired on the same day as the disposal first, then shares acquired in the 30 days after the disposal, then the section 104 holding, in which all earlier shares are pooled and treated as acquired at their average cost. It is mandatory for UK purposes.

The US works differently. IRS Publication 550 at https://www.irs.gov/publications/p550 explains that if you can adequately identify the shares you sold, their basis is the cost of those particular shares. Where shares are held by a broker, adequate identification means telling the broker which lot to sell at the time of the sale and receiving written confirmation within a reasonable time. If you cannot adequately identify the shares, the basis is that of the shares acquired first. The publication is clear that, except for certain mutual fund shares, you cannot use an average price per share for ordinary stock.

UK brokers rarely record lot selections, so most UK sales in a US catch-up are matched first-in, first-out against the oldest lot, which can produce a very different dollar basis from the UK pooled cost. Our dedicated guide to the section 104 pool and US basis covers the reconciliation in detail.

What goes into US cost basis: stamp duty, dealing costs and corporate actions?

The Form 8949 instructions describe basis as usually the cost of the property, including the purchase price and costs of purchase such as commissions. For UK shares the main purchase costs are the broker's dealing charge and Stamp Duty Reserve Tax. GOV.UK at https://www.gov.uk/tax-buy-shares says that buying shares usually attracts a tax or duty of 0.5% on the transaction, paid as SDRT when shares are bought electronically. In our view both the dealing charge and the SDRT paid on purchase are costs of acquiring the shares and belong in column (e), translated at the purchase date rate.

UK practice is consistent with this. GOV.UK at https://www.gov.uk/tax-sell-shares/work-out-your-gain lists stockbrokers' fees and SDRT paid when the shares were bought among the costs that can be deducted in working out a UK gain. Platform custody and annual account charges are not costs of a particular trade and should not be added to basis.

Corporate actions need their own reconstruction. Rights and bonus issues, consolidations, scrip dividends and share-for-share takeovers change the number of shares and how basis is spread. Publication 550 gives worked examples of allocating basis to rights, and HS284 notes that UK reorganisations are not treated as acquisitions; the two systems are similar but not identical, so apply each event separately on each side.

Do wash sales and capital loss carryovers apply to UK shares?

Yes, both apply to foreign shares exactly as they do to US ones. Publication 550 describes a wash sale as selling stock at a loss and, within 30 days before or after the sale, buying substantially identical stock. The loss is disallowed, reported with code W, and added to the basis of the new shares. UK investors who sell and repurchase the same holding, for example around the end of the UK tax year, can trigger this without realising, because the UK 30-day rule works differently and only looks at acquisitions after the disposal.

Net capital losses are limited on the US side: Publication 550 sets the annual deduction against other income at the lesser of $3,000 ($1,500 if married filing separately) or the net loss, with the unused balance carried forward. In a multi-year catch-up, carryovers must be rolled forward year by year in sequence, because a loss in an early missed year changes the tax in every later one. We have a separate guide on rebuilding capital loss carryovers across late years.

Which records do you need to rebuild from UK contract notes and statements?

Because nothing has been reported to the IRS, the records are the return. Before any figures go onto Form 8949, assemble the following for every holding sold in the catch-up years, and for the purchases behind them, however long ago they were made:

Contract notes for every purchase and sale, showing trade date, settlement date, quantity, price, consideration, commission and SDRT.
Annual or tax-year statements from each platform, used to confirm opening and closing positions and to catch trades with missing contract notes.
Records of corporate actions affecting each holding: rights, bonus and scrip issues, consolidations, demergers and takeovers.
Dividend reinvestment records, since each reinvestment is a new lot.
Your filed UK Self Assessment returns and the capital gains pages, SA108, for the same years, with the UK computations behind them.
UK Capital Gains Tax payment records, needed to support the foreign tax credit and to fix the translation date for the tax paid.
A dated exchange rate table, with its source, covering every trade date and tax payment date.

How do you claim UK Capital Gains Tax against US tax on Form 1116?

The foreign tax credit depends first on where the gain is sourced. IRS Publication 514 at https://www.irs.gov/publications/p514 explains that, in most cases, gain on personal property sold by a US resident is US source and gain on property sold by a nonresident is foreign source. For this purpose a US citizen with a tax home abroad is treated as a nonresident for a sale of personal property only if an income tax of at least 10% of the gain is paid to a foreign country. A UK resident US citizen who pays UK Capital Gains Tax at the current rates will normally clear that 10% threshold, making the gain foreign source and creditable.

Gains sheltered by the UK annual exempt amount or UK losses may bear little UK tax, so the 10% test can fail, leaving the gain US source. A US person who sold UK shares while living in the US is usually in the same position. Publication 514 also describes treaty re-sourcing, which requires a separate Form 1116 limitation, but notes that this rule does not apply to income re-sourced under treaty relief provisions that apply solely to US citizens resident in the treaty country; whether US-UK treaty re-sourcing helps in a given case needs to be checked against the treaty itself rather than assumed.

Two further mechanics matter. Portfolio share gains generally fall in the passive category, although the high-taxed income rules can move income out of it. And Publication 514 requires capital gain rate differential adjustments to foreign source capital gains when computing the Form 1116 limitation, so a long-term gain taxed at preferential US rates supports less credit than the raw figure suggests. Where UK tax exceeds the US limit, Publication 514 allows a one-year carryback and then a ten-year carryover of the unused foreign tax.

What does UK Capital Gains Tax look like on the same share sales?

On the UK side, gains on shares held outside an ISA are subject to Capital Gains Tax after deducting allowable costs and the annual exempt amount. GOV.UK at https://www.gov.uk/capital-gains-tax/rates states that, for gains made from 6 April 2026, the rate is 18% on gains falling within the basic rate band and 24% above it, and that the tax-free allowance for the 2026 to 2027 tax year is £3,000. Rates and the annual exempt amount have both changed in recent years, so each catch-up year must use the figures that applied to that UK tax year rather than today's.

Gains are reported on the capital gains summary pages, SA108, of the SA100 tax return; HMRC publishes it at https://www.gov.uk/government/publications/self-assessment-capital-gains-summary-sa108 and it is updated each year. Remember that the UK tax year runs from 6 April to 5 April while the US year is the calendar year, so a single UK return will often contain sales that fall in two different US years. Mapping each sale to both years is an early step in any rebuild.

Worked scenario: one investor, two UK share sales, two different answers

The following is an illustration with assumed figures and assumed exchange rates, not a real client and not actual historic rates. A US citizen who has lived in London for many years, has never filed US returns and holds a UK platform account sold two holdings in calendar 2023.

Holding A, long-term: bought on 10 March 2021 for £400,000, plus £2,000 commission and £2,000 SDRT, for a total cost of £404,000. At an assumed rate of 1.39 dollars to the pound, the US basis is $561,560. Sold on 14 September 2023 for £440,000 less £1,000 commission, net proceeds £439,000. At an assumed 1.24, US net proceeds are $544,360. The UK gain is £35,000, but the US result is a long-term loss of $17,200, reported in Part II with box F checked, because sterling fell while the shares were held.

Holding B, short-term: bought on 16 January 2023 for £100,000 plus £500 commission and £500 SDRT, a cost of £101,000. At an assumed 1.21, US basis is $122,210. Sold on 11 October 2023 for £130,000 less £600 commission, net £129,400, which at an assumed 1.22 is $157,868. The UK gain is £28,400 and the US short-term gain is $35,658, reported in Part I with box C checked.

Both sales fall in the UK 2023 to 2024 tax year, giving total UK gains of £63,400. Assume, for illustration, UK Capital Gains Tax of £11,000 was paid, translated at an assumed 1.25 on the payment date, or $13,750. On the US return, the long-term loss offsets the short-term gain, leaving a net short-term gain of $18,458 taxed at ordinary rates. At an assumed US marginal rate of 35%, the US tax on that net gain is about $6,460. The Form 1116 limitation caps the credit at roughly that amount, so most of the UK tax cannot be used in 2023 and is instead carried back or forward, subject to the limits in Publication 514.

In this illustration £63,400 of UK gains becomes a US net gain of about $18,000, and the excess UK tax becomes a carryover that may be usable in later years. Copying the UK figures across at one rate would have overstated US income substantially.

How do you file late years with UK share sales: the Streamlined route?

For a US person living in the UK whose failure to file was non-willful, the Streamlined Foreign Offshore Procedures are usually the cleanest path. The IRS page at https://www.irs.gov/individuals/international-taxpayers/us-taxpayers-residing-outside-the-united-states requires delinquent or amended returns for the three most recent years for which the due date has passed, with all required information returns, and delinquent FBARs for the six most recent years. The non-residency test is met if, in any one of the last three years, you had no US abode and were outside the United States for at least 330 full days, and the failures must be non-willful, meaning due to negligence, inadvertence, mistake or a good faith misunderstanding of the law.

A taxpayer who qualifies and follows the instructions is not subject to failure-to-file, failure-to-pay, accuracy-related, information return or FBAR penalties; tax and interest are still payable. Each return carries the Form 8949 and Schedule D reconstruction described above, and a signed certification of non-willful conduct accompanies the package. Late FBARs are filed electronically through FinCEN's BSA E-Filing System at https://bsaefiling.fincen.treas.gov, selecting Other as the reason for late filing and entering Streamlined Filing Compliance Procedures in the explanation box. The IRS Delinquent FBAR Submission Procedures page was withdrawn around 1 July 2026 and should not be relied on as a separate route.

Sales before the three-year window still matter, because they set loss carryovers and, through first-in, first-out matching, decide which lots remain. A US person living in the US falls under the domestic version instead, which carries a 5% miscellaneous offshore penalty.

Missed US tax returns with UK share sales: a checklist

List every disposal by trade date and map each to both its US calendar year and its UK tax year.
Rebuild each holding's purchase lots, including dividend reinvestments and corporate actions, from contract notes and statements.
Apply first-in, first-out matching unless written lot identification exists; do not use the section 104 average cost.
Translate cost and purchase costs at purchase-date rates, and proceeds net of selling costs at sale-date rates, from one documented source.
Classify each sale as short-term or long-term using trade dates, and report on Form 8949 box C or box F.
Check for wash sales around any loss sale and roll capital loss carryovers forward year by year.
Test each sale against the 10% UK tax rule before treating the gain as foreign source on Form 1116.
Translate UK tax at the payment-date rate, apply rate differential adjustments, and track unused credits.
File FBARs for the account through the BSA E-Filing System alongside the returns.

Failure modes we see when UK share sales are reconstructed

The same errors recur across the catch-up files we take over. The first is copying the SA108 totals onto Schedule D after a single currency conversion. The second is using the section 104 average cost as US basis. The third is using settlement dates rather than trade dates, which can flip a sale between short-term and long-term.

Others are quieter: checking box A or box D, which implies a Form 1099-B exists; leaving SDRT and commission out of basis; claiming the full UK tax as a credit without the source rule, limitation or rate differential adjustment; and ignoring sales before the filing window, which leaves later basis and carryovers wrong.