US and UK Tax Advisors Working for a UK Employer Guide |

US and UK Tax Advisors Working for a UK Employer Guide |

US and UK Tax Advisors: Working for a UK Employer Guide

US and UK Tax Advisors on UK Employment Tax

US and UK tax advisors who advise Americans employed by UK companies prepare the most common cross-border return profile in the United Kingdom: a US citizen receiving a sterling salary through UK PAYE, paying UK income tax and National Insurance, and filing an annual Form 1040 that must correctly report the same salary in US dollars with the foreign tax credit applied to eliminate the UK income tax already deducted at source. Furthermore, the UK employment package typically includes elements that create specific US compliance obligations beyond the salary itself — employer pension contributions that qualify for the Article 17 treaty exemption, equity awards that require PFIC or cost basis analysis, and a UK bank account for the salary that is FBAR-reportable from the first month of employment. Additionally, the interaction between the UK PAYE year — which runs April to April — and the US calendar year — which runs January to December — creates a timing difference in the income and tax figures that US and UK tax advisors must resolve correctly before the Form 1116 foreign tax credit calculation can be completed. Consequently, understanding every element of the UK employment package and its US tax treatment is the starting point for every US and UK tax advisor's engagement involving an American employed in the United Kingdom.

UK PAYE: The Foundation of the UK Employment Tax Position

How UK PAYE Works

UK PAYE — Pay As You Earn — is the system through which the employer deducts UK income tax and National Insurance contributions from the employee's gross salary each pay period and remits them directly to HMRC. Furthermore, the employer uses a tax code issued by HMRC to calculate the monthly income tax deduction — the most common tax code for a standard UK employee, reflecting the personal allowance is 1257L. Additionally, the annual P60 document — issued by the employer after 5 April each year — confirms the total gross salary, total income tax deducted, and total NIC deducted for the UK tax year. Consequently, the P60 is the primary source document for the UK side of the US and UK tax advisors' annual return, confirming the UK employment income and the UK income tax figure that feeds into the Form 1116 foreign tax credit calculation. The HMRC PAYE guidance is at https://www.gov.uk/paye-for-employers.

The UK Tax Year vs the US Calendar Year

The UK tax year runs from 6 April to 5 April the following year — meaning the P60 for the UK tax year ending 5 April 2025 covers the period April 2024 to April 2025. Furthermore, the US Form 1040 covers the calendar year from 1 January to 31 December 2024 — overlapping with but not matching the UK P60 period. Additionally, the income and UK tax figures from the April-to-April P60 must be adjusted to a January-to-December basis for the Form 1040 — using payslips for January to March and April to December of the same calendar year, respectively. Consequently, US and UK tax advisors use the monthly payslip data — rather than the annual P60 — to allocate UK employment income and UK income tax correctly to the US calendar year, since using the P60 directly produces a misaligned figure that may over- or understate both the income and the creditable foreign tax. The IRS Form 1040 guidance is at https://www.irs.gov/forms-pubs/about-form-1040.

The Foreign Tax Credit on UK Employment Income

How the Credit Is Calculated

The UK income tax deducted through PAYE on employment income is a creditable foreign income tax — claimable on Form 1116 in the general income basket against the US income tax on the same employment income. Furthermore, the credit reduces the US income tax on the UK salary dollar-for-dollar — up to the credit limitation, which is the US tax attributable to the UK-source employment income. Additionally, where the UK income tax rate (20%, 40%, or 45%) exceeds the equivalent US income tax rate on the same income, excess foreign tax credits arise that carry forward for up to ten years in the general income basket. Consequently, for most UK higher-rate taxpayers paying 40% or 45% UK income tax on employment income above the higher rate threshold, the foreign tax credit eliminates the US income tax on that income, producing zero net US income tax on the UK salary after the credit. The IRS Form 1116 guidance is at https://www.irs.gov/forms-pubs/about-form-1116.

NIC Is Not Creditable on Form 1116

National Insurance contributions deducted through PAYE alongside income tax are not creditable on Form 1116 — NIC is a social security contribution rather than an income tax. Furthermore, US and UK tax advisors must separate the monthly PAYE deduction into its income tax component and its NIC component before completing Form 1116 — using only the income tax figure as the creditable amount. Additionally, the P60 confirms the total income tax and total NIC separately, making this separation straightforward from the annual document. Consequently, including NIC in the Form 1116 calculation overclaims the foreign tax credit and produces an incorrect return — a common error made by non-specialist US preparers who treat the entire PAYE deduction as creditable foreign tax. HMRC NIC guidance is at https://www.gov.uk/national-insurance.

The Article 17 Pension Exemption for UK Employer Contributions

What Article 17(2) Provides

Article 17(2) of the US-UK Double Taxation Convention provides that employer contributions to a UK-registered pension scheme are excluded from US gross income in the year they are made, matching the deferral available to US 401(k) participants on employer contributions. Furthermore, this exemption must be actively claimed each year by filing Form 8833 with the Form 1040 — without Form 8833, the IRS treats the employer pension contribution as taxable compensation in the year it is paid. Additionally, the Article 17(2) exemption applies to employer contributions only — the employee's own pension contributions are not deductible for US income tax purposes. Consequently,US and UK tax advisors include Form 8833 as a standard annual attachment to every US return where the UK employer makes pension contributions — since the failure to file Form 8833 means the employer contribution is taxable US income and the employee has been overpaying US income tax. The US-UK treaty is at https://www.gov.uk/government/publications/usa-tax-treaties.

How to Calculate the Excluded Amount

The excluded amount on Form 8833 is the employer's contribution to the UK pension during the US calendar year — converted from sterling to US dollars at the IRS annual average exchange rate. Furthermore, employer pension contributions are typically disclosed on the employee's monthly payslip or on the annual pension benefit statement from the pension provider. Additionally, where the employer contributes a percentage of salary — for example, 10% of gross salary — the annual excluded amount in US dollars is calculated as the annual sterling contribution at the IRS annual average rate. Consequently, the Article 17(2) exclusion amount is straightforward to calculate, where the pension contribution is disclosed on the payslip — and US and UK tax advisors obtain this figure from the payslip data as part of the annual document collection process.

FBAR and UK Salary Accounts

The UK Salary Account Is FBAR-Reportable

The UK bank account into which the employer deposits salary is a foreign financial account for FBAR purposes — it must be reported annually where the aggregate balance of all foreign accounts exceeds $10,000 at any point during the calendar year. Furthermore, the FBAR balance for the salary account is the highest balance during the calendar year — not the year-end balance — meaning a salary deposit that temporarily elevates the balance significantly above the month-end balance must be captured. Additionally, the FBAR is filed electronically through the FinCEN BSA E-Filing System — separately from the Form 1040 — by 15 April, with an automatic extension to 15 October. Consequently, every American employed by a UK company who has a UK bank account for salary receipt has an annual FBAR obligation from the first full month of UK employment, and US and UK tax advisors file the FBAR as a standard annual deliverable alongside the Form 1040. The FinCEN FBAR guidance is at https://www.fincen.gov/financial-crimes-enforcement-network/fbar.

Equity Awards: Shares and Options From UK Employers

RSU Vesting as a US Taxable Event

Restricted stock units granted by a UK employer vest as US taxable income in the year of vesting — the fair market value of the shares on the vesting date is included in US gross income as compensation. Furthermore, the UK employer typically deducts UK income tax and NIC through PAYE on the same vesting income in the UK pay period of vesting — creating a UK tax payment that is creditable on Form 1116. Additionally, the US cost basis for the vested shares is the fair market value on the vesting date converted to US dollars at the vesting-date spot exchange rate — a figure that must be recorded at the time of vesting to support the Schedule D calculation on any future sale. Consequently, US and UK tax advisors must identify RSU vesting events in each tax year and include the vesting income on the US return — converting at the vesting-date rate — alongside the corresponding UK PAYE deduction as a Form 1116 creditable tax. The IRS RSU guidance is at https://www.irs.gov/taxtopics/tc427.

Share Option Exercises

Where the UK employer grants share options — whether EMI options, CSOP options, or unapproved options — the exercise of those options creates a US taxable event. Furthermore, for options treated as non-qualified stock options for US purposes (the most common treatment for UK options), the spread at exercise — the difference between the market price and the exercise price — is US ordinary income in the year of exercise. Additionally, where the UK option exercise triggers UK income tax through PAYE — as it does for unapproved options and some approved option schemes — the UK income tax is creditable on Form 1116 against the US ordinary income tax on the same spread. Consequently, US and UK tax advisors must review the specific UK option plan rules each time an option is exercised to confirm the correct US tax treatment — since the treatment differs between EMI, CSOP, SAYE, and unapproved options in ways that affect the Form 1116 credit availability.

The UK Self-Assessment and US Return Coordination

When UK Self-Assessment Is Required

A UK-employed American may need to file a UK self-assessment return in addition to having income tax deducted through PAYE — specifically where their total income exceeds £100,000 (creating a personal allowance restriction), where they have untaxed income from sources other than employment, or where HMRC specifically requests a return. Furthermore, the UK self-assessment is due online by 31 January following the end of the UK tax year — providing a natural sequencing window before the US extended filing deadline of 15 June or 15 October. Additionally, the confirmed UK income tax figure from the self-assessment — rather than just the PAYE figure from the P60 — is the more accurate input to the Form 1116 calculation where a self-assessment balancing payment was also made. Consequently, US and UK tax advisors always confirm whether a UK self-assessment return is required for each client before completing the Form 1116, and where it is required, complete the UK self-assessment first to obtain the final confirmed UK tax figures. The HMRC self-assessment guidance is at https://www.gov.uk/self-assessment-tax-returns.

Coordinating the UK and US Filing Sequence

The correct filing sequence for an American employed by a UK company is: complete the UK self-assessment by 31 January, confirm the UK income tax figures, prepare the Form 1040 with Form 1116 using those confirmed figures, file the Form 1040 and FBAR by 15 June or 15 October. Furthermore, preparing the Form 1040 before the UK self-assessment is complete risks using an estimated UK tax figure that may differ from the actual tax — requiring an amended return. Additionally, the UK P60 figures for the April-to-April tax year and the calendar year payslip allocation must both be completed before the Form 1116 is finalised. Consequently, the annual US and UK tax advisors engagement for a UK-employed American follows this fixed sequencing rule — UK first, US second, FBAR simultaneous with the US return.

Case Study: American Software Engineer at UK Tech Company

Our team prepares the annual UK and US returns for a US citizen working as a software engineer at a London technology company. Furthermore, his compensation package includes a base salary of £85,000, employer pension contributions of £8,500 per year (10% of salary), annual RSU vesting of approximately 500 shares at approximately £18 per share on the vesting date, and a UK current account for salary receipt. Additionally, he has no other UK income sources.

The annual US and UK tax advisors' filing package covers the following. The UK self-assessment is completed first in January — reporting the full salary, confirming the PAYE income tax deduction of approximately £24,800 for the calendar year, and confirming no self-assessment balancing payment is due. Furthermore, Form 8833 claims the Article 17(2) exemption for the £8,500 employer pension contribution — approximately $10,800 at the annual average rate — excluded from US gross income. Additionally, the RSU vesting of 500 shares at £18 per share on the vesting date produces US ordinary income of approximately $11,380 (500 × £18 = £9,000 converted at the vesting-date rate of 1.264), with the corresponding UK PAYE deduction on the vesting income credited on Form 1116. The Form 1116 general basket credit for the UK income tax on salary and RSU vesting income eliminates the US income tax. The FBAR lists the UK current account at its highest annual balance of approximately £18,500. Total net US income tax due: zero. Annual filing cost: UK self-assessment plus Form 1040 with Form 1116, Form 8833, and FBAR.

Common Mistakes for UK-Employed Americans

Using the P60 Directly Without Calendar Year Adjustment

The most common technical error on the US return for UK employees is using the P60 income and tax figures directly — without adjusting from the April-to-April UK tax year to the January-to-December US calendar year. Furthermore, the income and tax figures for January to March fall in one UK tax year and one US calendar year — while the income and tax figures for April to December fall in both the same UK tax year and the same US calendar year. The correct approach requires US and UK tax advisors to use the monthly payslip data to build a calendar-year allocation of both income and tax — producing the correct figures for the US return. HMRC PAYE guidance is at https://www.gov.uk/paye-for-employers.

Not Filing Form 8833 for Employer Pension Contributions

Many US preparers who handle UK employment returns overlook the Article 17(2) employer pension exemption — either because they are unaware of it or because they do not file Form 8833 for treaty-based positions. Furthermore, the failure to claim the Article 17(2) exemption results in the employer pension contribution being included as taxable US compensation — producing unnecessary US income tax on an amount that is legally treaty-exempt. The correct approach requires US and UK tax advisors to include Form 8833 as a standard annual attachment for every UK employee whose employer makes pension contributions — confirming the excluded amount and the treaty article relied upon.

Not Including RSU Vesting Income on the US Return

A significant number of UK-employed Americans with RSU grants do not report the RSU vesting income on the US return, assuming the UK PAYE deduction at vesting satisfies both countries simultaneously. Furthermore, the UK PAYE does not satisfy the US income reporting obligation — the vested income must appear on Form 1040 as ordinary compensation in the year of vesting. The correct approach requires US and UK tax advisors to identify every RSU vesting event in the calendar year, calculate the US dollar income at the vesting-date spot rate, include it in US gross income, and claim the corresponding UK PAYE deduction as a Form 1116 credit. The IRS RSU guidance is at https://www.irs.gov/taxtopics/tc427.

How US-UK Tax Can Help

At US-UK Tax, our team of Enrolled Agents, Chartered Tax Advisers, and Certified Public Accountants provides specialist US and UK tax advisorsfor Americans employed by UK companies. Furthermore, we complete the UK self-assessment first each January, allocate income and tax to the correct calendar year from payslip data, prepare Form 1116 using only creditable income tax — excluding NIC, file Form 8833 for the Article 17(2) employer pension exemption, report RSU vesting income with the vesting-date dollar conversion, prepare the Schedule D cost basis for vested shares, and file the FBAR for the UK salary account. Additionally, we prepare the annual review of any equity award vesting or option exercise events to ensure complete reporting.

Contact our team today. Email hello@us-uktax.com call 0333-8807974, or visit https://www.us-uktax.com/contact/.

Conclusion

Americans employed by UK companies face a coordinated annual filing obligation in both countries — the UK self-assessment where required, the US Form 1040 with Form 1116 and Form 8833, and the FBAR for the UK salary account. Furthermore, US and UK tax advisors who complete the UK self-assessment first, allocate income and tax to the correct calendar year from payslip data, claim the Article 17(2) employer pension exemption on Form 8833, and include RSU vesting income at the correct vesting-date dollar rate, ensure the annual filing is complete, accurate, and the foreign tax credit eliminates the net US income tax. Moreover, NIC must always be excluded from the Form 1116 calculation — the single most common error in non-specialist UK employment return preparation. Contact US-UK Tax at hello@us-uktax.com or call 0333-8807974 today.

Contact Us

US-UK Tax | hello@us-uktax.com | 0333-8807974

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FAQs

Q: Must I file a US tax return while employed by a UK company?

A: Yes. US citizens must file Form 1040 annually, reporting all worldwide income. UK employment income is reported on Form 1040 with the foreign tax credit on Form 1116 for UK PAYE income tax — typically eliminating the net US income tax. The FBAR is also required for the UK salary bank account.

Q: Is my UK employer pension contribution US-taxable?

A: No, where you claim the Article 17(2) exemption on Form 8833. Employer contributions to a UK-registered pension scheme are excluded from US gross income in the year of contribution, matching the 401(k) deferral treatment. Without Form 8833, the IRS treats the contribution as taxable compensation.

Q: Why is National Insurance not creditable on Form 1116?

A: NIC is a social security contribution, not an income tax. The Form 1116 foreign tax credit is available only for creditable income taxes — NIC does not qualify. Only the UK income tax component of the PAYE deduction is creditable. Including NIC overclaims the credit and produces an incorrect return.

Q: How do I report RSU vesting from my UK employer?

A: The fair market value of shares on the vesting date — converted to US dollars at the vesting-date spot exchange rate — is US ordinary income in the year of vesting. The corresponding UK PAYE deduction on the vesting income is creditable on Form 1116. The vesting-date dollar value becomes the US cost basis for any future share disposal.

Q: Why is the P60 not used directly for the US return?

A: The P60 covers the UK tax year from 6 April to 5 April, which does not align with the US calendar year from 1 January to 31 December. Monthly payslip data must be used to allocate income and UK income tax to the correct calendar year for the Form 1040 and Form 1116 calculations.

Q: Do I need a UK self-assessment return as a UK employee?

A: Possibly. A UK self-assessment return is required where total income exceeds £100,000, where there is untaxed income beyond employment, or where HMRC requests a return. Where self-assessment is required, it should be completed before the US return to obtain confirmed UK tax figures for the Form 1116.