Cross-Border RSU Tax: Why the Vest Follows You Out of Britain
Cross-border RSU tax is the single most expensive thing that wealthy Americans in Britain get wrong, and the damage almost never shows up until the shares have already been sold. Your restricted stock units were granted in one country. They vested in another. Two revenue authorities now claim the same block of income, using different rules, different dates and different currencies. Furthermore, neither authority will tell you that the other one has a claim.
Most readers arrive at this page after a specific shock. Perhaps your employer withheld UK PAYE on a vest that landed six months after you moved to New York. Perhaps your Form W-2 shows the entire vest as US wages, while an HMRC coding notice demands tax on most of it as well. Therefore, the arithmetic looks impossible. In practice, the arithmetic is entirely soluble, and the reason is worth stating plainly.
Double taxation on equity awards is almost never a feature of the rules. Instead, it is a mechanical failure of sourcing, of credit timing, or of documentation. Get the workday split right, claim the correct relief in the correct year, and the combined burden falls back to roughly the higher of the two national rates. Get it wrong, and a cross-border RSU tax position can exceed seventy per cent of the gross vest.
At TaxYork we prepare returns for senior technology employees, investment bankers, private equity professionals and founders who move between London and the United States. In our experience, the same four mistakes recur in nearly every unrepaired cross-border RSU tax file we inherit. This guide covers all of them, and it goes considerably further than the general articles currently ranking for this subject.
The Three Dates That Drive Cross-Border RSU Tax
Every cross-border RSU tax calculation turns on three dates: grant, vest and sale. Grant creates no tax charge in either country, because a restricted stock unit is only a contractual promise to deliver shares. Vest converts that promise into employment income in both systems simultaneously. Sale, finally, produces a capital gain or loss measured from the vest-date value.
Consequently, the period between grant and vest does the heavy lifting in every cross-border RSU tax computation. That window is the period over which you earned the award, and it is the window both HMRC and the Internal Revenue Service use to decide how much of the income belongs to each country. Additionally, the sale date matters for an entirely separate reason, because residence at the point of disposal governs the capital gains treatment.
Notably, this is where most published guidance stops. However, a serious cross-border RSU tax analysis has to go further, because the two systems apply that same earning period through completely different statutory machinery. The United Kingdom apportions by workdays. The United States taxes citizens on worldwide income regardless of workdays, then hands back a credit. Understanding that asymmetry is the whole game.
Why RSUs Behave Differently from Share Options
Restricted stock units are not share options, and they are not restricted stock either. Specifically, an option gives you the right to buy at a fixed price, so the tax event is exercise. Restricted stock gives you shares immediately, subject to forfeiture, which is why a Section 83(b) election exists for it. An RSU gives you neither, so no election is available.
That distinction has real money attached. Under Section 83 of the Internal Revenue Code, an 83(b) election accelerates tax to the grant date, locking in a low value before the shares appreciate. Nevertheless, the election requires an actual transfer of property, and an unvested RSU is merely an unsecured promise. Therefore, you cannot make an 83(b) election on an RSU, and any adviser who suggests otherwise has misread the award agreement.
The consequence for cross-border RSU tax planning is significant. You cannot fix the value early, so you cannot control which country you live in when the value crystallises. Instead, you control the workday record, the withholding mechanics and the credit claims. Those three levers are where the money actually sits.
How HMRC Splits Your Vest by Workdays
HMRC does not tax the whole vest simply because you once lived in London, and it does not surrender the whole vest simply because you have left. Rather, the United Kingdom taxes the slice of the award that relates to UK workdays during the earning period. That principle sits at the heart of every cross-border RSU tax analysis involving Britain.
The rules apply whether you arrived in the UK mid-award or departed mid-award. Moreover, they apply even when you hold no UK residence at all on the vest date, which surprises most people meeting cross-border RSU tax rules for the first time. Leaving Britain does not erase a UK-source slice that you have already earned, and HMRC has both the treaty and the domestic legislation to collect it.
The Relevant Period Under Chapter 5B
The internationally mobile employee rules in Chapter 5B of Part 2 of the Income Tax (Earnings and Pensions) Act 2003 define a "relevant period" for each award. For a restricted or forfeitable security, HMRC's Employment Related Securities Manual confirms that the period runs from the award of the security to the lifting of the restriction or forfeiture condition. In plain terms, grant to vest.
HMRC then apportions the vest value by reference to the number of workdays performed in each territory during that relevant period. Consequently, if you worked 870 UK days out of 1,043 total workdays between grant and vest, then 83.4 per cent of that vest is UK employment income. The remaining 16.6 per cent falls outside the UK charge entirely.
Importantly, the manual stresses that HMRC applies time apportionment on the facts rather than by rigid formula. Therefore, your workday record is evidence, not decoration. We ask every client to reconstruct a contemporaneous calendar showing location by working day, because a cross-border RSU tax position defended on estimates is a position that invites enquiry. HMRC's guidance on the Statutory Residence Test sets out the day-counting conventions that the same records will support.
The 2026/27 UK Rates Applied to Your Vest
For a high earner, the UK slice attracts income tax at the additional rate. Income tax rates for 2026/27 charge 20 per cent on the basic rate band, 40 per cent above it, and 45 per cent on taxable income exceeding £125,140. The personal allowance of £12,570 tapers away entirely once adjusted net income reaches £125,140, which any meaningful vest will breach on its own.
National Insurance deserves separate attention, because it is where a genuine saving often hides. Employer and employee rates for 2026 to 2027 set primary Class 1 contributions at 8 per cent between the primary threshold of £12,570 and the upper earnings limit of £50,270, then 2 per cent above. Employers pay 15 per cent above a secondary threshold of just £5,000.
However, National Insurance follows social security law rather than income tax law. Accordingly, where a certificate of coverage places you inside the US social security system at the chargeable event, the UK contribution may fall away even though income tax does not. That single point has saved clients five-figure sums, and almost no competing article on cross-border RSU tax mentions it.
The Section 222 Make-Good Trap
Here is the trap that ranks first on our list of expensive surprises, and it appears in none of the leading pages on this topic. When your employer operates PAYE on a share vest, the tax is due on a notional payment. Frequently, the sell-to-cover proceeds do not raise enough cash to settle the full liability, particularly at the 45 per cent additional rate.
Section 222 of ITEPA 2003 then bites, and it belongs on every cross-border RSU tax checklist. HMRC's Employment Income Manual confirms that if you fail to make good the shortfall to your employer within 90 days of the end of the tax year in which the chargeable event falls, the unpaid amount becomes additional taxable employment income. For a vest in the 2026/27 tax year, the deadline is 5 July 2027.
The penalty is brutal in its simplicity. Tax on tax. A £39,570 shortfall left unpaid becomes £39,570 of fresh earnings, generating roughly £17,807 of further tax at 45 per cent. Furthermore, HMRC confirms that making good need not be in cash, so returning shares of equivalent value can satisfy the obligation. Consequently, a diarised reminder is worth thousands of pounds.
How the IRS Taxes the Same Vest
The United States takes a fundamentally different route to the same income. As a US citizen or green card holder, you are taxed on worldwide income wherever you live and wherever you worked. Therefore, the IRS does not apportion your vest at all. It taxes one hundred per cent of it, then offers relief for the foreign tax you paid on the foreign-source part.
That asymmetry explains why so many cross-border RSU tax files look catastrophic before they are repaired. On the face of the documents, the UK has taxed 83 per cent and the US has taxed 100 per cent. Nevertheless, the relief mechanisms are perfectly capable of closing that gap, provided you claim them correctly and in the right year.
Section 83 and the 2026 Withholding Numbers
For US purposes, the vest is compensation under Section 83, and it enters Box 1 of your Form W-2 at the fair market value on the vesting date. Your employer must withhold. IRS Publication 15 sets the supplemental wage withholding rate at 22 per cent for the first $1 million of supplemental wages in a calendar year, rising to 37 per cent above that threshold.
That 22 per cent rate is the root of a very common cash-flow shock. A senior executive taxed at a 37 per cent marginal federal rate is under-withheld by fifteen percentage points on every dollar of the vest. Conversely, an executive whose UK tax has already been collected at 45 per cent is often massively over-withheld once the foreign tax credit is applied. Either way, the cross-border RSU tax outcome depends on the return, not on the payslip.
Social security limits also matter to the final cross-border RSU tax figure. For 2026 the Social Security Administration sets the wage base at $184,500, above which the 6.2 per cent old-age element stops. Medicare continues without limit at 1.45 per cent, plus the 0.9 per cent Additional Medicare Tax above $200,000 for single filers and $250,000 for joint filers.
Why the Foreign Earned Income Exclusion Rarely Rescues a Vest
Many Americans abroad assume the Foreign Earned Income Exclusion will absorb their equity income. In reality, it rarely does more than nibble at the edges. The IRS confirms that the exclusion applies only to foreign earned income, and the 2026 ceiling stands at $132,900 following the inflation adjustments in Revenue Procedure 2025-32.
Three problems follow immediately for a cross-border RSU tax client. First, your salary usually consumes the entire exclusion before the vest is even considered. Secondly, only the foreign-workday portion of the vest qualifies as foreign earned income at all. Thirdly, and most importantly, electing the exclusion strips the excluded income out of the foreign tax credit calculation, which typically destroys more value than it creates for a high earner.
Therefore, we almost always recommend the foreign tax credit route for a cross-border RSU tax client rather than the exclusion. The credit scales with your actual UK tax, which at 45 per cent comfortably exceeds the US federal rate. The exclusion, by contrast, is capped at a figure most of our clients pass in February. Form 2555 remains available, but revoking a prior election carries a five-year lockout, so the decision deserves proper modelling.
FICA, National Insurance and the Totalisation Certificate
Social security is the quiet third tax in every cross-border RSU tax calculation, and clients routinely forget it. The United States and the United Kingdom operate a totalisation agreement precisely to stop both systems charging the same earnings. The IRS explains that a certificate of coverage evidences which system applies to a given period of employment.
For equity income the certificate carries real weight. Where the certificate places you in the US system at the time of the chargeable event, the UK employer should not be charging primary Class 1 contributions on that vest. Conversely, where you remain in the UK system, FICA should not apply to the same income. Additionally, employers who ignore the certificate frequently over-collect on both sides, and recovering those contributions requires a formal claim.
We therefore treat the certificate as a core document in every file. The Social Security Administration's guidance on the UK agreement sets out the application process and the evidence required. Without it, a cross-border RSU tax position can carry an entirely avoidable 8 per cent or 7.65 per cent overlay.
Treaty Sourcing and Foreign Tax Credits
The treaty is what converts two overlapping claims into one net liability. Article 14 of the US-UK double taxation convention sources employment income to the place where the work is performed, which is the same workday logic HMRC applies domestically. Consequently, the UK-workday slice of your vest is UK-source and the US-workday slice is US-source.
That sounds tidy, and for a non-American it largely is. In practice, however, the saving clause preserves the United States' right to tax its own citizens as if the treaty did not exist. Therefore, the treaty alone does not solve a cross-border RSU tax problem for an American. The Foreign Tax Credit does the real work, and the treaty then patches the gaps the credit cannot reach.
Re-Sourcing Under the US-UK Treaty
Consider the awkward case that breaks a naive cross-border RSU tax calculation. You worked in New York for part of the earning period, so that slice is US-source. Suppose the UK nonetheless taxes some element of it, or suppose your circumstances place UK tax on income the IRS treats as domestic. A credit normally requires foreign-source income, so a US-source item would generate no relief at all.
The relief-from-double-taxation article solves this by re-sourcing. Specifically, it treats the relevant US-source income as arising outside the United States, but solely for foreign tax credit purposes. The IRS instructions to Form 1116 require a separate form for each category of income re-sourced by treaty, which is why these returns run to several pages of computation.
Practitioners skip this constantly. In our experience reviewing inherited files, a missing re-sourced basket is the second most common defect in a cross-border RSU tax return, behind only a missing workday schedule. Furthermore, the omission is entirely recoverable, because amended returns claiming foreign tax credits enjoy an unusually long window. The full treaty text and technical explanation sit on the IRS site, and the US Treasury's tax treaty library holds the signed originals.
The Timing Mismatch That Wrecks Credit Claims
Here is the structural problem that no competing article addresses properly. The UK tax year ends on 5 April, and the balancing payment for a vest is due by 31 January following. The US tax year ends on 31 December. Therefore, a vest on 1 May 2026 sits in the UK's 2026/27 year, with UK tax payable on 31 January 2028, while the US 2026 return falls due in 2027.
By default, the Foreign Tax Credit underpinning your cross-border RSU tax claim uses the cash basis. Under that method you credit foreign taxes in the year you actually pay them, which in the example above means claiming 2026 US relief for tax paid in 2028. That mismatch strands the credit in the wrong year and can waste it entirely.
The solution is the election to claim foreign taxes on the accrued basis. Once made, the election is irrevocable and binds every future year, so it demands care. Nevertheless, for a client with recurring annual vests it aligns the two systems permanently and eliminates the mismatch at source. Getting this election right is the difference between a cross-border RSU tax file that works and one that leaks money every single year.
Carrybacks, Carryforwards and the Ten-Year Window
Excess credits are not lost, which is why a cross-border RSU tax review should always run across multiple years. Where your UK tax exceeds the US tax on the same income, the surplus carries back one year and forward ten. Consequently, a 45 per cent UK charge against a 37 per cent US charge builds a credit bank that later sheltering years can draw on. We routinely find clients sitting on six-figure carryforwards they never knew existed.
The claim window is also unusually generous. Ordinary refund claims expire after three years, but a claim arising from foreign taxes runs for ten years from the due date of the return for the year in which the foreign taxes were paid or accrued. Therefore, a 2018 vest mishandled at the time may still be fixable today through an amended Form 1040-X.
That ten-year window is the most valuable single fact in this article. Additionally, it cuts both ways, because a later HMRC adjustment that reduces your UK tax triggers a mandatory notification to the IRS. Ignoring that obligation converts a technical correction into a compliance failure, so any cross-border RSU tax review should examine open years in both countries together. Our tax treaty optimisation service exists precisely for this analysis.
Selling the Shares After the Vest
Vesting and selling are two separate taxable events, and conflating them produces the third classic error. The vest is employment income. The sale is a capital transaction measured from the vest-date value, and it follows an entirely different set of rules in each country.
Selling immediately at vest is therefore the cleanest outcome, because it produces a negligible gain. Holding, by contrast, opens a second cross-border RSU tax exposure that grows with the share price and with every currency movement in between.
Two Cost Bases, Two Currencies
Every cross-border RSU tax file carries two cost bases for the same shares. Your US cost basis equals the vest-date fair market value in dollars. Your UK cost basis equals the same value converted to sterling at the vest date. Consequently, the two bases diverge the moment the exchange rate moves, and a single sale can produce a dollar gain alongside a sterling loss, or the reverse.
That is not a rounding error. A pound moving from $1.20 to $1.35 changes a sterling-measured gain by more than twelve per cent, entirely independently of the share price. HMRC publishes monthly exchange rates for conversion, while the IRS accepts consistently applied spot or average rates. Therefore, document your chosen method and apply it uniformly.
UK capital gains rates now sit at 18 per cent within the basic rate band and 24 per cent above it, with the annual exempt amount at £3,000 for 2026/27. US long-term rates of 0, 15 and 20 per cent apply only where you have held the shares for more than twelve months after vesting. Additionally, the 3.8 per cent Net Investment Income Tax attaches to the US gain, and no foreign tax credit offsets it in the ordinary way.
Temporary Non-Residence and the Return to Britain
Leaving Britain does not always end the UK's interest in your gains. The temporary non-residence rules recapture certain gains realised while you were away if you resume UK residence within five years. HMRC's helpsheet HS278 explains that the period of non-residence must exceed five years for the rules to fall away entirely.
The practical consequence is stark. Sell your vested shares during a three-year secondment to San Francisco, then return to London, and those gains land in your year of return. Therefore, a departure that looks like a clean break can generate a UK charge two or three years later, when the cash has long since been spent.
We accordingly build the five-year test into every departure plan. Furthermore, the interaction with US residence rules can be favourable if you time disposals correctly, which is why a cross-border RSU tax review should always precede a relocation rather than follow it. Our cross-border planning service models these scenarios before the move.
Reporting the Accounts That Hold Your Shares
Vested shares sit somewhere, and that somewhere carries its own reporting obligations. Clients who handle the income analysis perfectly still trip over the account-level reporting, and the penalties there are disproportionate to the tax at stake. Consequently, a complete cross-border RSU tax engagement covers the accounts as well as the income.
Reporting failures also travel further than tax errors. Specifically, an unreported account can extend the assessment window and undermine an otherwise clean compliance history. MoneyHelper's guidance on shares and investments offers a plain-English starting point, although neither UK nor US reporting duties are covered there in full.
FBAR and Form 8938 on Your Brokerage Account
If your employer's share plan administrator holds your shares in a US account, no FBAR arises from that account alone. However, many UK-listed employers and several international plan administrators use accounts in Britain, Jersey or Ireland. FinCEN requires an FBAR where the aggregate value of your foreign financial accounts exceeds $10,000 at any point in the calendar year.
Form 8938 operates separately under FATCA and captures specified foreign financial assets. For Americans living abroad the thresholds are $200,000 at year end or $300,000 at any time for single filers, and $400,000 or $600,000 respectively for joint filers. Therefore, a substantial vest held in a non-US account frequently triggers both filings in the same year. Our FBAR and FATCA service handles these together.
Notably, the shares themselves held directly in a US brokerage account are not FBAR-reportable, whereas the account holding them abroad is. That distinction confuses almost everybody, and it explains a large share of the missed FBAR cases we repair each year. Therefore, confirm the custodian's jurisdiction before concluding your cross-border RSU tax reporting is complete.
Employer filings offer a useful cross-check. Your plan documents and your employer's disclosures on the SEC's EDGAR database will identify the award terms, the vesting schedule and the administrator. Additionally, those documents establish the grant date that anchors the whole apportionment.
Self Assessment, SA102 and SA106
On the UK side, a vest taxed through PAYE still usually requires a Self Assessment return, because the employment page must reconcile the reported figures. Non-residents with UK-source employment income report on the residence pages as well. Consequently, the return becomes a document that has to agree with your US filing rather than contradict it.
Foreign income and foreign tax credit relief go on the foreign pages. Meanwhile, disposals of the vested shares belong on the capital gains summary. HMRC's Self Assessment guidance sets out the deadlines, and the online filing date of 31 January follows the end of the tax year.
Consistency between the two returns matters enormously to a durable cross-border RSU tax position. In our experience, enquiries begin when the UK figure and the US figure describe the same vest differently without explanation. Therefore, we prepare both sides from a single reconciled workpaper, which is the core of our US and UK tax returns preparation work.
Fixing Missed Cross-Border RSU Tax Reporting
Many readers will recognise themselves in the errors above, and several will realise they have unfiled years behind them. That situation is common, it is fixable, and the routes are well established. Above all, act before either authority contacts you, because voluntary correction preserves options that enforcement removes.
The IRS Streamlined Foreign Offshore Procedures
Where your failure to report was non-wilful, the IRS Streamlined Filing Compliance Procedures allow you to file three years of amended or delinquent returns and six years of FBARs. For taxpayers meeting the foreign residency test, the offshore penalty is waived entirely, leaving only the tax and interest.
Equity income makes these submissions technically demanding, because a Streamlined package is really three years of cross-border RSU tax work compressed into one filing. Specifically, each year requires a fresh workday apportionment, a fresh foreign tax credit computation and a fresh currency conversion. Furthermore, the non-wilfulness certification on Form 14653 must describe your circumstances accurately, because a defective certification undermines the entire submission. Our IRS Streamlined Filing service prepares these end to end.
Timing rewards the prompt. The programme remains discretionary, and eligibility closes once the IRS opens an examination. Additionally, the Delinquent FBAR Submission Procedures were withdrawn on 1 July 2026, which removed one of the softer landing options that older articles still describe as available.
Correcting the UK Side
HMRC has its own routes, and they run on separate clocks. Where you have underpaid UK tax on a vest, an unprompted disclosure attracts materially lower penalties than a prompted one. The discovery assessment window extends to four years for innocent error, six years for careless behaviour and twenty years for deliberate conduct.
Offshore matters carry a further uplift, which makes early correction still more valuable. Consequently, we usually sequence the UK disclosure and the US submission deliberately rather than filing both blindly on the same day. That sequencing protects the foreign tax credit position, since the credit depends on tax actually paid or accrued.
Both authorities respond well to clear, well-evidenced computations. Therefore, a properly documented cross-border RSU tax correction, supported by workday records and payroll data, resolves far more quickly than a bare set of amended figures.
Case Study: A London Technology Executive with a $540,000 Vest
The following cross-border RSU tax case shows the arithmetic end to end. Consider a client we shall call the London executive, a US citizen who joined a New York-listed technology group in London on 1 May 2022 and received an award of 12,000 restricted stock units vesting annually over four years. They relocated to the New York office on 1 September 2025. The final tranche of 3,000 shares vested on 1 May 2026 at $180 per share, producing gross income of $540,000.
The relevant period ran from 1 May 2022 to 1 May 2026, covering 1,043 workdays. Of those, 870 were UK workdays and 173 were US workdays. Consequently, HMRC's share of the vest was 83.4 per cent, or $450,360. At an assumed rate of $1.27 to the pound, that produced UK employment income of approximately £354,600.
UK income tax at the additional rate of 45 per cent came to £159,570, roughly $202,654. Critically, no primary Class 1 National Insurance arose, because a certificate of coverage had placed the executive inside the US social security system from 1 September 2025. That single document saved a five-figure contribution that the payroll had initially proposed to deduct.
The US position looked alarming before relief. The full $540,000 appeared in Box 1 of the Form W-2, and the employer withheld at the 22 per cent supplemental rate, giving $118,800. Meanwhile, the executive's marginal federal rate was 37 per cent, implying a headline federal charge of roughly $199,800 on the vest alone.
The foreign tax credit then did the work that defines a competent cross-border RSU tax return. Foreign-source income of $450,360 supported a general-basket limitation of approximately $166,633, so the entire UK charge up to that ceiling became creditable. The surplus of about $36,021 carried forward for ten years. Only the US-workday slice of $89,640 remained genuinely US-taxable, generating roughly $33,167 of federal tax.
The combined cross-border RSU tax outcome was $235,821 on $540,000, an effective rate of 43.7 per cent. Without the workday apportionment and the credit claim, the same vest would have carried $402,454, or 74.5 per cent. Therefore, the analysis was worth $166,633, and the $85,633 of over-withheld federal tax came back as a refund.
One further trap nearly cost more. The sell-to-cover raised only £120,000 against a PAYE liability of £159,570, leaving a shortfall of £39,570. The executive made that amount good to the employer before 5 July 2027, the 90-day deadline following the end of the 2026/27 tax year. Had they missed it, Section 222 would have converted the shortfall into fresh taxable earnings, adding roughly £17,807 of avoidable tax.
Common Cross-Border RSU Tax Mistakes We See Every Year
Patterns repeat across our cross-border RSU tax caseload with remarkable consistency. Accordingly, this section sets out the failures we correct most often, so that you can test your own position against them before a revenue authority does it for you.
Treating the Payslip as the Answer
Payroll systems handle one country at a time. Therefore, your UK payslip reflects a UK view of the vest and your Form W-2 reflects a US view, and neither reconciles the other. Clients who assume the withholding is the final answer routinely overpay, because the credit that fixes a cross-border RSU tax position lives on the return rather than in the payroll run.
Over-withholding is the more common outcome for additional-rate taxpayers. Specifically, UK PAYE at 45 per cent plus US supplemental withholding at 22 per cent removes 67 per cent of a vest in cash, against a properly computed liability closer to 44 per cent. Consequently, the refund is real money sitting with two governments until you claim it.
Losing the Workday Record
Workday evidence decays fast. Calendars get deleted, travel systems get decommissioned and employers change share plan administrators. Nevertheless, HMRC will expect you to justify the apportionment years after the event, and an estimate offered without support invites a wider enquiry.
We therefore ask clients to export travel and calendar data annually rather than at the point of crisis. Furthermore, boarding passes, hotel records and building access logs all corroborate a workday schedule. A defensible cross-border RSU tax apportionment rests on contemporaneous evidence, and reconstructing it later costs several times what preserving it would have done.
Ignoring the Second and Third Tranches
An award vesting over four years produces four separate calculations, each with its own relevant period and its own workday ratio. However, clients frequently apply the first year's percentage to every subsequent tranche. That shortcut skews the cross-border RSU tax result in whichever direction the move happened to run.
The error compounds for anyone who moves twice. Additionally, each tranche interacts with a different set of exchange rates, tax bands and credit carryforwards. Modelling all outstanding tranches together, rather than one at a time, usually reveals timing choices worth more than the compliance fee.
How TaxYork Can Help with Cross-Border RSU Tax
We prepare US and UK returns together, from one reconciled set of workpapers, for clients whose equity awards straddle both systems. That integrated approach is the only reliable way to run a cross-border RSU tax position, because a US return prepared without the UK numbers will always understate the credit available.
Our cross-border RSU tax work begins with the award documents and the workday record rather than the payslip. Subsequently, we build the apportionment, model the credit against the exclusion, test the accrual election and check the social security position. Finally, we reconcile the two filings so that HMRC and the IRS see consistent figures describing the same event.
For clients with unfiled years we handle the full remediation, including Streamlined submissions, delinquent FBARs and UK disclosures, alongside the underlying cross-border RSU tax computations. Furthermore, we review open years for unclaimed credits, since the ten-year window frequently yields refunds that clients had written off. Explore our full range of US personal tax services to see how the pieces fit together.
Conclusion
Cross-border equity compensation is not inherently punitive. Instead, it is unforgiving of poor records and late claims. The UK taxes your workdays, the US taxes your citizenship, and the treaty plus the foreign tax credit reconcile the two into a single sensible number. A well-run cross-border RSU tax position should land close to the higher of the two national rates, not the sum of them.
Three actions protect a cross-border RSU tax outcome. Keep a contemporaneous workday calendar from grant to vest. Diarise the Section 222 make-good deadline of 5 July following the tax year of the vest. Model the foreign tax credit and the accrual election before you file, rather than after. Consequently, the arithmetic stops being a threat and becomes a plan.
Above all, review your open years. Ten years of amendable returns represents real recoverable money for anyone who has vested equity across the Atlantic since 2016. Therefore, the sooner a specialist looks at the file, the more of it you keep.
Contact Us
If your restricted stock units vested around a move between Britain and the United States, we can review the position and quantify what is recoverable. Speak to our team on 020 3488 8606 or email hello@taxyork.com. Alternatively, book a consultation and we will assess your cross-border RSU tax exposure across both countries.
Disclaimer
This article provides general information about cross-border RSU tax rules and does not constitute tax advice for any particular person. Tax legislation, rates and thresholds change, and the treatment of any award depends on your individual circumstances, residence position and the terms of your plan documents. You should obtain professional advice before acting. TaxYork accepts no liability for any action taken in reliance on this article.
Written by the TaxYork Expert Team — US-UK tax specialists.