US UK Tax Deadlines 2027: Dual Filing Calendar for Americans

The US UK tax deadlines 2027 for an American living in Britain are: 31 January 2027 for the UK 2025/26 Self Assessment return and payment; 15 April 2027 for the 2026 Form 1040, any US balance and the FBAR; 15 June 2027 automatically for filers abroad; and 15 October 2027 on extension for both the 1040 and the FBAR.

For a high-earning American in London, the list of dates is not the hard part. The hard part is order. Each UK figure has to be final before the matching US figure can be built, and a payment made in the wrong week can cost interest. This guide sets out every date that matters in one calendar. It then explains which date drives which number, using a worked example for a London executive with UK salary and a US brokerage account. The dates and the sequencing come from the cross-border return preparation work we do at Jungle Tax.

Why do Americans in the UK face two tax calendars?

The US tax year is the calendar year. The UK tax year runs from 6 April to 5 April. Every US return therefore covers parts of two UK tax years. The 2026 Form 1040 covers 1 January to 31 December 2026, which includes the last three months of UK 2025/26 and the first nine months of UK 2026/27. Under its citizenship-based rules the US taxes you on your worldwide income wherever you live. The UK taxes its residents on their worldwide income too. The US–UK income tax treaty, and the foreign tax credit rules on each side, stop the same pound being taxed twice. They only work if each return draws on the right figures from the other.

In practice this means three things:

• The UK return usually comes first. Your 2025/26 UK liability is fixed by the 31 January 2027 return, months before any US 2026 deadline.
• The US return depends on the UK one. The foreign tax credit you claim on Form 1116 is only as reliable as the UK liability behind it.
• Payments and filings come apart. The IRS charges interest from 15 April 2027 on any unpaid 2026 tax, even if you extend the filing date. HMRC's payment dates fall in January and July whatever date you file.

The merged 2027 calendar, month by month

The table below puts every date that affects a typical wealthy US citizen resident in the UK in date order. Each date is taken from current GOV.UK or IRS guidance. Where a 2027 date is not yet in an official 2027 publication, the table says so.

Date	Authority	What is due	Status
15 January 2027	IRS	Fourth estimated tax payment (Form 1040-ES) for tax year 2026	Published on the 2026 Form 1040-ES
31 January 2027 (a Sunday)	HMRC	2025/26 online Self Assessment return; balancing payment for 2025/26; first payment on account for 2026/27	Published on GOV.UK
5 April 2027	HMRC	End of the 2026/27 UK tax year	Fixed by statute
6 April 2027	HMRC	Start of 2027/28. Making Tax Digital for Income Tax becomes mandatory for sole traders and landlords whose 2025/26 qualifying income was over £30,000	Published on GOV.UK
15 April 2027 (a Thursday)	IRS / FinCEN	2026 Form 1040 original due date; payment deadline for any 2026 balance; first 2027 estimated payment; FBAR for calendar 2026	Statutory date; no weekend shift in 2027
31 May 2027	HMRC (employer)	Employers must give employees their 2026/27 P60	Standing PAYE rule
15 June 2027 (a Tuesday)	IRS	Automatic two-month extended filing date for US citizens whose tax home and residence are outside the US; second 2027 estimated payment	Standing rule (Publication 54)
6 July 2027	HMRC (employer)	Employers must give employees their P11D (benefits in kind) for 2026/27	Standing PAYE rule
31 July 2027 (a Saturday)	HMRC	Second payment on account for 2026/27	Published on GOV.UK
7 August 2027	HMRC	First quarterly Making Tax Digital update (period 6 April to 5 July 2027) for those mandated from April 2027	Published on GOV.UK
15 September 2027	IRS	Third 2027 estimated tax payment	Statutory pattern; confirm on the 2027 Form 1040-ES
5 October 2027	HMRC	Deadline to register for Self Assessment if you first had untaxed income in 2026/27	Standing rule
15 October 2027 (a Friday)	IRS / FinCEN	Extended 2026 Form 1040 deadline if Form 4868 was filed in time; automatically extended 2026 FBAR deadline	Standing rule
31 October 2027 (a Sunday)	HMRC	Paper Self Assessment return deadline for 2026/27	Standing rule
7 November 2027	HMRC	Second quarterly Making Tax Digital update (6 July to 5 October 2027)	Quarterly pattern on GOV.UK
15 December 2027	IRS	End of the discretionary additional extension for filers abroad who asked for it by letter before 15 October	Discretionary; not automatic
30 December 2027	HMRC	File the 2026/27 return online by this date if you want a small balance collected through your PAYE tax code	Standing rule
January 2028	IRS	Fourth 2027 estimated payment. 15 January 2028 is a Saturday, so the date moves to the next business day	Not yet confirmed; check the 2027 Form 1040-ES
31 January 2028	HMRC	2026/27 online return; balancing payment for 2026/27; first payment on account for 2027/28	Standing rule

Two of the HMRC dates in 2027 fall at weekends: 31 January and 31 July. HMRC does not move its deadlines for weekends. Electronic payments should be sent early enough to arrive by the deadline. A Sunday deadline is not a reason to send the money on Monday.

Quarter by quarter: what you are actually doing

• January to March 2027. Finish and file the UK 2025/26 return, and pay the balance and the first 2026/27 instalment. Make the last 2026 US estimated payment. Start collecting US year-end tax forms (1099s from US brokers) and UK year-end statements.
• April to June 2027. Pay any expected US 2026 balance by 15 April, even if you are not filing yet. File the FBAR by 15 April if you can. Decide whether to file the 1040 by 15 June or extend to October. Collect the 2026/27 P60.
• July to September 2027. Collect the P11D. Pay the second UK instalment by 31 July. Prepare the UK 2026/27 return early (the timing section below explains why). Make the 15 September US estimated payment.
• October to December 2027. File the extended 1040 and FBAR by 15 October. Check whether any new UK income source needs Self Assessment registration by 5 October. Submit the UK 2026/27 return by 30 December if you want a small balance coded out.

The sequencing problem: which return has to come first?

Most deadline guides list the dates and stop there. For a high earner the more important question is how the two returns feed each other.

The IRS lets most US citizens abroad claim foreign taxes on an accrual basis. Once a cash-basis filer makes that election, it is binding for later years. Under the accrual rules, a foreign income tax generally accrues on the last day of the foreign tax year. The UK 2025/26 tax year ends on 5 April 2026, which falls inside the US 2026 tax year. On that reading, the 2025/26 UK liability is the main foreign tax figure for the 2026 Form 1040. That is the number HMRC fixes when you file by 31 January 2027.

Some preparers instead split UK tax across the two UK years that overlap the US calendar year. Whichever method is used, it has to be applied consistently, and it has to be supported by final UK numbers rather than payslip estimates. In both cases the UK return comes before the US return.

Decision table: which date drives which number

Number needed	Where it comes from	Date it becomes reliable	US 2026 return it feeds
Total UK income tax liability for 2025/26	Filed 2025/26 SA return (SA100 plus supplementary pages)	31 January 2027 (earlier if filed earlier)	Form 1116 foreign taxes accrued (accrual basis)
Split of UK tax between employment income and investment income	2025/26 tax calculation (SA302 or software equivalent)	31 January 2027	Allocation between the general and passive categories on separate Forms 1116
UK credit for US tax on US-source dividends	2025/26 return, foreign pages (SA106)	31 January 2027	Treaty re-sourcing calculation under Article 24
UK salary for January to April 2026	2025/26 P60 and final payslips	31 May 2026	Foreign earned income on the 1040
UK salary for April to December 2026	Monthly payslips; 2026/27 P60	31 May 2027	Foreign earned income on the 1040
Benefits in kind for 2026/27	2026/27 P11D	6 July 2027	Taxable compensation on the 1040, often missed when the 1040 is filed before July
US brokerage dividends and gains	US Forms 1099 (consolidated)	Mid-February to March 2027, sometimes corrected later	Schedule B, Schedule D and Form 8949
Highest balance of each UK account in 2026	UK bank, ISA and pension statements	Early 2027	FBAR and Form 8938

Look at the P11D row. A UK executive with significant benefits in kind, such as private medical cover, a company car, or employer-paid accommodation or school fees, does not get the final benefits figure until July. A US return filed in April or June on payslip figures alone can understate US income. That is one practical reason many senior executives in London use the October extension.

Worked example: a London executive with UK salary and US brokerage income

All figures below are illustrative and rounded. They show the sequence, not a full tax calculation.

Facts. Catherine is a US citizen who has lived in London for six years. She is UK resident and taxed on the arising basis. Her salary is £320,000 a year through PAYE, and her employer provides private medical insurance and a car allowance. She keeps a US brokerage account that produced about $90,000 of US-source qualified dividends and $70,000 of long-term capital gains in calendar 2026. She also holds a stocks and shares ISA and a UK workplace pension, and the combined balances of her non-US accounts are well above the FBAR threshold.

Step 1 — January 2027: file the UK 2025/26 return

Her 2025/26 Self Assessment return reports the PAYE salary and benefits, plus the US dividends and gains received between 6 April 2025 and 5 April 2026, converted into sterling. On the foreign pages she claims UK foreign tax credit relief for US tax on the dividends. Under the treaty, the UK credit is limited to the rate the US could charge a non-US person on portfolio dividends, generally 15%, even though she pays more than that to the IRS as a citizen. Suppose the return shows a total UK liability of about £150,000. About £135,000 of that relates to employment income and about £15,000 to her investment income after the treaty credit. She files and pays the balancing payment and her first 2026/27 payment on account by 31 January 2027.

Step 2 — April 2027: estimate and pay the US 2026 balance

Her UK tax on salary is well above the US tax on the same income, so the general-category credit should eliminate US tax on her wages. The passive category is different. The US taxes her dividends and gains first as a citizen, and the UK credit only offsets part of that. Any residual US tax, including the 3.8% net investment income tax that a foreign tax credit cannot normally offset, is due on 15 April 2027. She pays an estimate by that date and files Form 4868. Filing on 15 June would not stop interest running from 15 April on any unpaid balance.

Step 3 — July 2027: collect the P11D and the US corrected 1099s

Her P11D arrives in early July with the cash equivalent of her medical cover. Her broker issues a corrected 1099 that reclassifies part of one dividend. Both change the US return. Neither would have been captured by a June filing.

Step 4 — September 2027: draft the UK 2026/27 return early

The 2026/27 return is not due until 31 January 2028. Preparing it in September 2027 is still useful: it confirms the UK figures for the April to December 2026 part of her US year. Whichever foreign tax method her US return uses, the UK data behind it is now final rather than estimated. It also confirms the right size for her next UK payments on account.

Step 5 — October 2027: file the 1040 and FBAR

By 15 October 2027 she files the 2026 Form 1040. It includes two Forms 1116 (general and passive) and Form 8938 for her UK accounts. She files her FBAR the same week through FinCEN's BSA E-Filing System, listing every UK current account, savings account, ISA and pension account that has to be reported. The return is built entirely on UK figures that are already final, so a later amendment is unlikely.

What goes wrong if the order is reversed: if the US return is filed in March on payslip estimates, the credit is claimed against an unconfirmed liability. If the UK figure later changes, the US return may have to be amended. A reduction in foreign tax can also trigger a notification duty under the redetermination rules. Getting the order right avoids that work.

US vs UK: how the two systems handle deadlines

Feature	United States (IRS)	United Kingdom (HMRC)
Tax year	1 January to 31 December	6 April to 5 April
Main return in 2027	2026 Form 1040	2025/26 SA100 (online)
Original filing date	15 April 2027	31 January 2027 (online)
Extensions	Automatic to 15 June for filers abroad; to 15 October via Form 4868; possible discretionary extension to 15 December	No general extension; late filing triggers penalties unless you have a reasonable excuse
When tax must be paid	15 April 2027, whatever the filing date	31 January 2027 (balance and first payment on account); 31 July 2027 (second payment on account)
In-year prepayments	Quarterly Form 1040-ES (April, June, September, January)	Two payments on account; PAYE for employment income
Foreign account reporting	FBAR (FinCEN 114) and Form 8938	No equivalent annual account return; offshore income reported on the SA106
Digital reporting from April 2027	No equivalent	Making Tax Digital quarterly updates for qualifying sole traders and landlords

How do the IRS extensions work for Americans in the UK?

The IRS guidance for US citizens abroad (Publication 54) gives a two-month automatic extension, to 15 June, to taxpayers whose tax home and residence are outside the US and Puerto Rico on the regular due date. You attach a statement to the return explaining that you qualify. The extension covers filing only. Interest on unpaid tax runs from 15 April.

To reach 15 October you file Form 4868 by the date the return would otherwise be due. Filers abroad generally have until 15 June to do that. A further discretionary extension to 15 December can be requested by letter before 15 October. It is not automatic and should not be part of a normal plan. The FBAR follows its own rule: it is due 15 April and extended automatically to 15 October without any request. It does not get the December extension. Forms 8938 and 5471 are filed with the 1040, so they share its deadline and any extension.

What changes in the UK in April 2027?

Making Tax Digital for Income Tax at the £30,000 threshold

According to the GOV.UK Making Tax Digital guidance, sole traders and landlords whose qualifying income was over £30,000 in 2025/26 must use Making Tax Digital for Income Tax from 6 April 2027. Qualifying income means gross income from self-employment and UK or overseas property. Salary, dividends and gains do not count towards it. Those who crossed £50,000 in 2024/25 have been in the regime since April 2026, and a £20,000 threshold is planned for April 2028.

For an American in the UK this matters most if you rent out a property, in London or back in the US, or run a consulting business alongside employment. The 2025/26 return you file in January 2027 is the return that tests the threshold. Getting gross rents and fees right on that return decides whether MTD applies. Once you are in, you must keep digital records, send quarterly updates (the first due 7 August 2027) and make a year-end final declaration. MTD changes nothing on the US side. A US citizen landlord still reports the rental on Schedule E using calendar-year figures. In practice the MTD quarterly records make the January to December rebuild easier, because the UK data is already split by quarter.

Rate changes and the US credit

The government has announced higher UK income tax rates on property and savings income from 6 April 2027. Higher UK tax on rental income or interest increases the UK credit available against US tax on the same income. Because foreign tax credits are limited by category, the extra credit is only useful if there is US tax in the matching category to absorb it. Expect more excess credits to carry forward in the passive category.

When does the streamlined three-year lookback roll forward in 2027?

If you have missed US returns or FBARs, 2027 changes which years a catch-up filing covers. Under the Streamlined Foreign Offshore Procedures, a non-willful taxpayer abroad files the most recent three years of returns for which the due date (including properly applied-for extensions) has passed, and the most recent six years of FBARs for which the FBAR due date has passed. They also sign Form 14653 and pay any tax and interest due. For qualifying filers abroad there is no offshore penalty.

At the date of writing, November 2026, the three-year window covers 2023, 2024 and 2025. Once the 2026 return due date passes in 2027, 2026 enters the window and 2023 drops out. The FBAR window moves in the same way once the 2026 FBAR due date passes. Exactly which day applies (15 April, the automatic 15 June date for filers abroad, or 15 October on extension) depends on your own extension position and should be checked case by case. Two practical points follow:

• If an earlier year carries the larger liability, finishing a streamlined submission before the window moves can change which years you file and what you pay.
• A submission that straddles the roll date has to be rebuilt around the new set of years. Many late projects slip for this reason.

Our IRS streamlined filing team prepares these submissions for Americans in the UK, including unreported ISAs, UK pensions and missed Forms 8938 and 5471. Our FBAR penalty calculator shows the exposure the procedure is designed to remove.

Where do UK accounts appear on the 2027 US filings?

Wealthy Americans in Britain usually hold more reportable accounts than they realise. Plan for the following when preparing the April or October 2027 filings:

• Current, savings and deposit accounts: FBAR, and Form 8938 above the higher thresholds for filers abroad.
• Stocks and shares ISAs: reportable on the FBAR. The US does not recognise the ISA wrapper, so income and gains inside it are taxable on the 1040. UK-domiciled funds inside an ISA can raise passive foreign investment company (PFIC) reporting on Form 8621.
• UK workplace and personal pensions: generally listed on the FBAR and Form 8938. How they are treated on the 1040 depends on the type of plan and on the treaty.
• Personal companies: a UK company you control can require Form 5471, due with your 1040.

Practical checklist for the 2027 cycle

• File the UK 2025/26 return well before 31 January 2027, so the US preparer has the final liability and the tax calculation in February.
• Decide by 15 April 2027 whether you are filing in June or October. Pay a reasoned US estimate either way.
• Diarise 31 May (P60) and 6 July (P11D). Do not finalise the 1040 until both are in hand.
• If you have rental or self-employed income, check your 2025/26 gross figures against the £30,000 MTD test before 6 April 2027.
• File the FBAR when the 1040 is filed, not separately at the end. The account balances are in the same set of statements.
• If any prior year is outstanding, confirm before spring 2027 which years the streamlined window covers.

For broader coverage of either system, see our UK tax services and our US–UK tax accountants page, or browse more cross-border guides.

Plan your 2027 filings in the right order

Missing a deadline is rarely what goes wrong in a dual filing year. The usual problem is filing the right forms with numbers built in the wrong order. Our team prepares UK Self Assessment and US federal returns together, so each 2027 return draws on final figures from the other, and we bring overdue years up to date through the streamlined procedures where needed. If you would like your 2027 calendar mapped against your own income, accounts and filing history, contact our cross-border team for a confidential consultation.