US Tax Advisor for Americans in London: Your Filing Year, Month by Month
Americans in London juggle two tax years, two currencies and a bonus season that falls between them. Here is the filing year month by month, the London situations that need most care, and a worked example of a typical City household.
Behind London's stucco terraces, many American households run two tax calendars at once, one ending in April and one in December.
Written by the US UK Tax Experts team, cross-border tax specialists
US tax advisor for Americans in London: an introduction
A US tax advisor for Americans in London earns their keep by managing the calendar as much as the forms. You file a US return on the calendar year and a UK return on a year ending 5 April. Bonuses, share vests and payments on account all fall at different points. Consequently, the right work done in the wrong month can still cost you money. This article walks through the year month by month, then covers the London situations that need most care.
For the full picture of filing in both countries, read our guide to US and UK tax returns. It sets out every return an American in Britain may need.
What a US tax advisor for Americans in London actually does
A cross-border preparer is a professional who prepares returns in two tax systems from one set of figures. For Americans in London, that usually means the Form 1040, the FBAR and a Self Assessment return. The work is mostly timing and reconciliation. In our experience, London households lose most money through credits claimed in the wrong year, not through missed forms.
What does the filing year look like from London?
The year has six fixed points: 31 January, 5 April, 15 April, 15 June, 31 July and 15 October. Most London households need action at each of them.
January: the UK return and the first payment
The GOV.UK page on Self Assessment deadlines sets 31 January 2027 for online returns for the 2025 to 2026 tax year. Any tax due must also be paid by then. Additionally, the first payment on account for the current year usually falls on the same day. January is therefore the busiest month for UK cash flow.
April: two year ends in ten days
The UK tax year ends on 5 April. Ten days later, on 15 April, your US return is nominally due. However, the IRS allows an automatic two-month extension to 15 June if you live abroad. The same page warns that interest runs on unpaid tax from the regular due date. Therefore, if you expect to owe US tax, pay an estimate by 15 April.
June and July: the US return and the second UK payment
Many London households file the US return by 15 June. By then, the UK figures for the year ended 5 April are usually known. Then, on 31 July, the second UK payment on account falls due. The GOV.UK page on payments on account explains when these are required. They are not needed if last year's bill was under £1,000, or if more than 80% of your tax was paid at source.
October: the extended US deadline and the FBAR
If you need more time, the six-month extension moves the US filing date to 15 October. The FBAR shares that date. The IRS page on the FBAR says it is due on 15 April, with an automatic extension to 15 October. You file it if your foreign accounts together exceed $10,000 at any time in the year.
December: closing the US year
The US tax year closes on 31 December, halfway through the UK year. This is the moment to note each account's highest balance for the FBAR. It is also when to record any share sales, because the US year will not reopen. Moreover, a planned home sale or large gift can fall either side of 31 December. Timing it is your decision, but a US tax advisor for Americans in London can show you the tax in each year before you choose.
Which London situations need the most care?
Five situations cause most London problems: bonuses, share awards, tax-free UK savings, selling a home and workplace pensions. Each is treated at a different time, or in a different way, in each country.
Bonuses paid in the first quarter
Many City firms pay bonuses between January and March. For the UK, a March bonus falls in the tax year ending that April. For the US, it falls in the calendar year it was paid. As a result, one bonus can sit in a different year on each return. The UK tax on it must then be matched to the right US year for the credit. A US tax advisor for Americans in London should split every payslip by date.
Restricted stock units and options
Share awards from US employers are common in London. Both countries usually tax restricted stock units at vest, but each sources them by working days. Our article on RSU tax in the US and UK explains the split. Options are timed differently again, and plans such as EMI have no US equivalent. Each award therefore needs its own schedule.
ISAs and UK funds
The GOV.UK page on Individual Savings Accounts confirms that ISAs are free of UK tax. The US does not recognise that. ISA interest, dividends and gains are reported on your US return. Moreover, UK funds held inside an ISA are usually passive foreign investment companies. They then need Form 8621 each year. We prepare that reporting; we do not recommend investments.
Selling a London home
GOV.UK's Capital Gains Tax rates page says you do not usually pay tax when you sell your home. The US is less generous. IRS Topic 701 lets you exclude up to $250,000 of gain, or $500,000 on a joint return. You must have owned and lived in the home for two of the last five years. London prices and currency movements can push a gain past those limits. Consequently, a sale that is free of UK tax can still produce a US bill.
UK workplace pensions
Most London employers enrol staff in a workplace pension. The UK gives tax relief on contributions, but the US does not automatically follow. Article 18 of the US-UK income tax treaty lets a US citizen working in the UK deduct or exclude contributions to a UK employer scheme. However, the relief cannot exceed what a corresponding US plan would allow. The claim is usually disclosed on Form 8833. Therefore, your pension figures need checking against the US limits each year, not copied from your P60.
A worked example: a London household's year
Consider a typical case. Daniel is a US citizen working for a bank in London. His wife Claire is British, and they have one child. Daniel receives a March bonus and US restricted stock units that vest each quarter. He also holds a stocks and shares ISA. This is an illustrative example, not a real client.
The first half of the year
In January, Daniel files his UK return for the year to the previous April and pays the balance. His bonus arrives in March and is taxed through PAYE. On 15 April, his US preparer estimates his US position. His UK tax on salary exceeds the US tax on it, so little is due. However, his ISA income and fund gains carry no UK tax to credit. He therefore pays a small estimate by 15 April to stop interest running.
The second half of the year
By June, the UK figures for the year to 5 April are final. Daniel's US return is filed on 15 June, with his FBAR soon after. Each quarterly vest is reported in both countries, at the rate on the vest date. In July, he makes his second UK payment on account. Nothing else is due until January.
What Daniel's year shows
Daniel's tax is not complicated, but his calendar is. Each payment depends on figures from the other country. A US tax advisor for Americans in London keeps those figures in one file, so each deadline uses the latest numbers.
How do you avoid paying tax twice from London?
You avoid it mainly through the foreign tax credit, which reduces US tax by UK tax paid on the same income. The UK's higher rates usually leave little US tax on salary.
The credit or the exclusion
The foreign earned income exclusion lets you leave a capped amount of foreign earnings out of US income. The cap is indexed each year. IRS Publication 54 says you cannot take a credit for tax on income you exclude. For most London earners, the credit works better, because UK tax often exceeds US tax. Excess credits can also be carried, under section 904(c) of the tax code, back one year and forward ten.
Where credits do not reach
Some US taxes sit outside the credit. The IRS net investment income tax questions and answers say foreign tax credits generally cannot reduce that 3.8% tax. It applies above $200,000 of modified adjusted gross income for single filers and $250,000 for joint filers. Some practitioners argue the US-UK treaty gives relief, but the point is contested. The cautious approach is to pay it and consider a protective claim.
When the UK gives the credit
Occasionally the UK must give relief instead, for example on US rental income. GOV.UK explains Foreign Tax Credit Relief on its page for people taxed twice. The US-UK income tax treaty decides which country goes first.
What should you look for in a US tax advisor for Americans in London?
Look for one process that covers both returns, a clear calendar and registration with the IRS. Fancy offices matter less than a reliable routine.
One file for both returns
Ask whether the same team prepares both returns. If not, ask who reconciles them. Our article on what goes wrong when two firms split your returns shows why this matters. A good US tax advisor for Americans in London owns the reconciliation.
A calendar you can see
Ask for the year's dates in writing, with what you must send before each one. Furthermore, ask how estimates are set for 15 April. Good preparers tell you early when a payment is coming.
Registration and scope
The IRS page on choosing a tax professional explains how to check a preparer. Also ask what the firm does not do. For example, we prepare and file returns; we do not give investment or financial advice.
What if you are behind with US filings?
If you have missed US returns while living in London, the usual route back is the Streamlined Foreign Offshore Procedures. They need three years of returns and six years of FBARs.
The Streamlined route
The IRS page for US taxpayers residing outside the United States sets the conditions. You must meet a non-residency test and certify that your failure was not wilful. Our guide to IRS Streamlined filing explains the steps. Late FBARs on their own are no longer a published penalty-free route, because the IRS removed that page in July 2026.
Starting the calendar again
Once you are compliant, the London calendar above takes over. The catch-up years feed the first normal year, because unused foreign tax credits carry forward. Similarly, the cost basis of ISA funds and shares set during the catch-up carries into later sales. Therefore, keep the catch-up working papers safe. Most people find the second year much easier than the first, as the figures and the routine are already in place.
How US UK Tax Experts can help
US UK Tax Experts prepares your US and UK returns together, from one file, on a calendar we agree with you at the start. We prepare the Form 1040, the FBAR, any Form 8621 and your Self Assessment. We also work out your 15 April estimate and your UK payments on account. Our US federal returns service and UK Self Assessment service set out what is included.
Conclusion
Living in London means two tax years, two currencies and a bonus season between them. The key dates are 31 January, 5 April, 15 April, 15 June, 31 July and 15 October. Bonuses, share awards, ISAs and home sales need the most care. A US tax advisor for Americans in London who keeps both returns in one file makes each date routine.
Contact us
If you need a US tax advisor for Americans in London, email hello@usuktaxexperts.com or use our contact form. Tell us about your income, any share awards and which years you have filed. We reply within one working day.
Frequently asked questions
The main dates are 31 January for the UK return and payment, 15 April for US payment, 15 June for the US return if you live abroad, 31 July for the second UK payment on account and 15 October for the extended US return and FBAR.
Not always. A bonus paid in March falls in the UK tax year ending that April, but in the US calendar year it was paid. The UK tax on it must be matched to the right US year for the foreign tax credit.
Possibly. You can exclude up to $250,000 of gain, or $500,000 on a joint return, if you owned and lived in the home for two of the last five years. Gains above that, including those caused by currency movements, are taxable in the US even if the UK charges nothing.
Some do and some do not, so ask. A US tax advisor for Americans in London who prepares both returns from one file can match each credit to the right year. If two firms are involved, one should own the reconciliation.
If you expect to owe, yes. The two-month extension for people abroad covers filing, but interest runs on unpaid tax from 15 April. Paying an estimate stops that interest.
It covers regular income tax on most UK income. The IRS says it generally cannot reduce the 3.8% net investment income tax, and income that carried no UK tax, such as ISA income, has no UK credit to offset it.
