Do I need a US tax preparer if I already have a UK accountant?

Yes. A UK accountant files the company's accounts and, usually, your UK Self Assessment return. Neither is a US filing. As a US citizen you file on worldwide income regardless of where you live, and your Form 1040, Form 1116, FBAR and any Form 5471 obligation sit entirely outside your UK accountant's remit. The two engagements share information but not responsibility, which is why the information request has to be explicit and dated.

Can I wait for my UK Self Assessment figures before filing my US return?

No, and this is the central problem. GOV.UK gives an online Self Assessment return a deadline of 11:59pm on 31 January following the end of the UK tax year, with the tax payable the same day. The US ladder for a calendar-year filer abroad runs to a regular April due date, an automatic two-month extension, a Form 4868 extension of six months in total, and at most a discretionary further two months requested by letter. All of those dates precede the following 31 January. The return is prepared from what is known, and the method choice handles the rest.

Does my UK PAYE tax count as a foreign tax credit on my US return?

Yes, subject to the Form 1116 limitation and the category rules. Publication 514 requires the credit to be computed separately for each income category, including general and passive category income, and credits do not cross between categories. That is why UK tax withheld on your salary cannot be used to shelter a dividend on your US return, even though a single HMRC relationship produced both.

Should I claim foreign taxes when paid or when accrued?

The default for a cash-method taxpayer is the year the tax is paid. Publication 514 allows an election to claim the credit in the year the tax accrues, made by checking the Accrued box in Part II of Form 1116. Accrual generally lines UK tax up with the income it relates to, which suits a founder whose UK tax is settled long after the US year closes. It is not reversible: Publication 514 states that once you make that choice you must follow it in all later years.

What happens if HMRC changes a figure after I have already filed my US return?

That is a foreign tax redetermination. Publication 514 directs the taxpayer to file Form 1040-X with a revised Form 1116 and a supporting statement where the change affects US tax liability, and Schedule C (Form 1116) where it does not. This is a normal part of a founder's compliance cycle rather than an error, and a properly scoped engagement expects it and budgets for it.

Does my UK company's bank account go on my personal FBAR?

It can. The FBAR reaches accounts in which you hold a financial interest, and ownership of a company above the regulatory threshold can attribute that company's own accounts to you personally. IRS.gov sets the filing trigger at an aggregate value of foreign financial accounts exceeding $10,000 at any time during the calendar year reported, due April 15 following that year with an automatic extension to October 15. That means your US preparer needs the company's account list and peak balances, which almost no founder thinks to request.

US Personal Tax Services for US Founders in the UK

US personal tax services for a founder running a UK company cover the individual filings that sit on top of the business: the federal return and its international schedules, the foreign tax credit computation, the annual foreign account report, the state position, and the estimated tax payments that stop interest running. None of that is the same work as the company accounts or the UK Self Assessment return, and a UK accountant who files both has still filed nothing with the IRS. The gap is rarely deliberate. It opens because the two tax calendars do not line up, and because nobody has been asked to own the personal US side across a full year.

What do US personal tax services actually cover for a UK-based founder?

A US citizen files on worldwide income wherever they live. IRS Publication 54 states that the regular due date for filing Form 1040 or Form 1040-SR is April 15 of the following year, and sets out the extensions available to a taxpayer whose tax home is abroad. Incorporating in England and Wales changes none of that. What it changes is the volume of information the personal return needs, and where that information sits: inside a company the founder controls, held by a UK accountant with no US filing obligation and no reason to produce figures cut to a US calendar.

A properly scoped personal engagement is preparation and compliance work delivered on a schedule. It covers the federal return with the international schedules the income mix requires, the FBAR, the state return where a state connection was never cleanly broken, quarterly estimated tax computations, and the reconciliation between UK and US amounts. It does not cover the company's own filings. And it does not begin in April, because by April the information window on the previous calendar year has been open and closing for months.

How do the UK and US tax calendars fail to line up?

GOV.UK confirms the UK tax year runs from 6 April to 5 April, that an online Self Assessment return must reach HMRC by 11:59pm on 31 January following the end of that year, and that the tax owed is payable by the same date. The US runs on the calendar year. For a founder drawing income from a UK company that creates a structural offset of roughly ten months between the point US tax on a slice of income falls due and the point UK tax on the same slice is quantified and paid. Follow a payment made mid-calendar-year:

Income paid in June falls in the UK tax year ending the following 5 April, and in the US calendar year ending that 31 December.
The US return for that calendar year is due the following April, with the extension ladder running out in December of the same year.
The UK return covering the same income is not due, and the balancing payment on it is not payable, until 31 January of the year after that.
Every US filing date available to the founder, including the last one, falls before that 31 January UK payment date.
So the UK tax figure the US return needs has not been quantified or paid at any point when the US return can still be filed on time.

What are the US filing deadlines for a founder living in the UK?

The structure matters more than any single date, because a deadline falling at a weekend or holiday shifts to the next business day. For calendar-year filers, IRS.gov and Publication 54 give the following ladder.

Regular due date: April 15. Interest runs from this date whatever else happens.
Automatic two-month extension, to June 15, for a taxpayer living outside the United States and Puerto Rico on the regular due date whose main place of business is also outside those areas. Publication 54 requires a statement attached to the return explaining which situation qualified you. The extension is automatic; the statement is not.
Form 4868, filed before the automatic two-month extension date, gives six months in total from the regular due date, to October 15, with the out-of-country box on line 8 checked.
A discretionary further two months, to December 15, requested by letter to the IRS by October 15 explaining why the time is needed. Discretionary, not automatic.
Form 2350 is a different instrument. IRS.gov describes it as for taxpayers who expect to file Form 2555 and need time to meet the bona fide residence or physical presence test. It is not a general extension for a founder waiting on UK numbers.
None of these is an extension to pay. IRS.gov is explicit that even if you are allowed an extension, you will have to pay interest on any tax not paid by the regular due date of your return.
FBAR runs on a separate track: IRS.gov gives it a due date of April 15 following the calendar year reported, with an automatic extension to October 15. A Form 4868 does nothing for it.

Which personal filings are routine, and which are triggered by events?

Scoping means separating the filings that recur every year from those that appear because something happened. Founders underestimate the second list, because the triggers feel like business milestones rather than personal tax events.

Routine: Form 1040 with the schedules the income mix requires.
Routine: Form 1116, computed separately for each category Publication 514 lists, including general and passive category income. Credits do not move between categories, so salary tax cannot rescue a dividend.
Routine: Form 2555 where foreign earned income is excluded. Salary can qualify; a dividend is not earned income and never falls inside it.
Routine: FinCEN Form 114, the FBAR, where aggregate foreign financial accounts exceeded $10,000 at any time in the calendar year reported.
Routine: Form 8938 where specified foreign financial assets exceed the reporting thresholds.
Routine: Form 5471 for the controlled foreign corporation, filed with the personal return, with schedules set by filer category.
Routine: estimated tax computations for each of the four payment periods, and a state return where a former state of residence still has a claim.

Event-driven: a share issue, a secondary sale, or an exit.
Event-driven: a shareholding change that moves the Form 5471 filer category, altering the schedules required without changing anything the founder notices.
Event-driven: opening or closing accounts, which alters the FBAR account list, including accounts the founder merely signs on.
Event-driven: arriving in or leaving the UK part way through a year, which splits the UK year but not the US one.
Event-driven: the first dividend year, which creates a Self Assessment liability where none existed and starts the payments on account cycle.
Event-driven: discovering earlier years were never filed, a separate remediation track under the streamlined procedures rather than part of a current-year engagement.

What does the US preparer need from the company and the UK accountant, and when?

This determines whether a return can be prepared at all, and no service page publishes it. The request goes out in January, against the calendar year just closed, and it names dates rather than UK-year documents.

Late January: the founder's personal payroll record for the calendar year, showing gross pay, UK income tax withheld under PAYE and National Insurance, split by payment date. A P60 reports the UK year to 5 April and is the wrong period.
Late January: a dividend register giving the date each dividend was declared and the date it was paid. The payment date drives the US year, and near a year end the two can fall in different years.
Late January: benefits and expense reimbursements reported to HMRC for the founder, with dates, so they can be re-cut to the calendar year.
February: the company's own bank, savings and payment processor accounts with peak balances during the calendar year, so FBAR ownership attribution can be tested.
February: the share register at the start and end of the calendar year, and every change in between.
March: the company's financial statements and tax computation, and the split of its accounting period across calendar years.
March: every payment the founder personally made to HMRC during the calendar year, with the date of each and the UK tax year it was applied to. This is the item most often missing, and the one the foreign tax credit computation turns on.
Continuously: any movement on a director's loan account between founder and company.

A worked example: Dana Ellis, a US founder in London

Dana Ellis is a US citizen resident in London and controlling shareholder of a UK company. The figures are illustrative and self-computed, shown to demonstrate the shape of the year rather than to predict a liability. During calendar year 2026 Dana takes salary of GBP 120,000, paid monthly, with GBP 39,000 of UK income tax withheld under PAYE across those twelve payments. On 30 June 2026 the company declares and pays her a dividend of GBP 200,000. It is her first dividend year; until then her only UK tax was PAYE, so on the GOV.UK payments on account rules she has no material instalments standing against the UK year the dividend falls in. Assume the UK tax attributable to that dividend, once computed, is GBP 64,000.

On the UK side, the dividend is income of the tax year ending 5 April 2027. Under the GOV.UK timetable the online return for that year is due by 11:59pm on 31 January 2028 and the tax is payable the same day, so the GBP 64,000 is a balancing payment made on 31 January 2028.

On the US side, the same dividend is income of calendar year 2026. Dana's Form 1040 for 2026 has its regular due date in April 2027. The automatic two-month extension carries her into June 2027, Form 4868 into October 2027, and a letter to the IRS at most into December 2027. Every one of those dates precedes 31 January 2028. There is no version of the US calendar in which she can wait for the UK number.

On the default cash method, the foreign taxes Dana can credit on her 2026 return are those actually paid during calendar 2026: the GBP 39,000 of PAYE, plus anything she paid HMRC personally in 2026 for earlier UK years. The GBP 64,000 is not among them. Her 2026 return shows a GBP 200,000 dividend with effectively no UK tax against it, and the resulting US tax falls due in April 2027 whether or not she has filed, because interest runs from the regular due date.

When the GBP 64,000 is paid on 31 January 2028 it lands in her 2028 calendar year on the cash method. If 2028 does not contain enough foreign-source income in the same Form 1116 category to absorb it, the credit is not lost but it has to travel: Publication 514 allows unused foreign tax to be carried back one year and forward to the ten years following the year it arose. Dana has paid US tax in 2027 and UK tax in 2028 on one dividend, and will spend two further filing seasons reconciling them.

Where does the foreign tax credit timing gap open, and how is it closed?

Publication 514 sets out the alternative. A taxpayer who otherwise uses the cash method may choose to claim the credit for foreign taxes in the year they accrue rather than the year they are paid, by checking the Accrued box in Part II of Form 1116. That aligns the UK tax with the income it relates to and closes most of the gap in Dana's example. Two consequences travel with it, and both belong in the engagement letter rather than a conversation the following spring.

First, it is not a one-year experiment. Publication 514 is explicit that once you make that choice, you must follow it in all later years and take a credit for foreign taxes in the year they accrue. It applies to all qualifying foreign taxes and cannot be switched on for a dividend year and off again afterwards.

Second, accrual imports its own mechanics. Publication 514 requires accrued foreign taxes to be translated at the average exchange rate for the tax year the taxes relate to, where they are paid within 24 months after the close of that year, are not denominated in an inflationary currency, and are paid during or after the year they relate to. An election to use the payment-date rate instead is available on a timely filed return. And because an accrued figure is an estimate until HMRC settles the position, a later change is a foreign tax redetermination: Publication 514 directs the taxpayer to file Form 1040-X with a revised Form 1116 and a supporting statement where US tax liability changes, and Schedule C (Form 1116) where it does not.

That is the part founders find surprising. Accruing does not remove work, it relocates it. The engagement acquires a standing obligation to revisit prior US years whenever a UK figure moves, which is why the choice of method must be documented and carried forward in the file.

How do UK payments on account and US estimated tax run on different clocks?

GOV.UK describes payments on account as two instalments due by midnight on 31 January and 31 July, each normally half the tax owed for the previous year, with a balancing payment due by midnight on the following 31 January where the actual liability is higher. They are not required where the previous year's Self Assessment bill was under GBP 1,000, or where more than 80 percent of that year's tax was collected at source.

The IRS runs an unrelated machine. IRS.gov states that individuals generally have to make estimated tax payments if they expect to owe $1,000 or more when the return is filed, that the year is divided into four payment periods, and that a taxpayer generally avoids an underpayment penalty by paying at least 90 percent of the current year's tax or 100 percent of the prior year's tax, whichever is smaller, with special rules for higher-income taxpayers. Publication 54 confirms these requirements are the same for a citizen abroad as for one at home.

The two systems do not know about each other. A founder who has just made a large 31 January payment to HMRC can still be short on US estimated tax for the same period, because the US safe harbour is computed on US liability alone and takes no account of UK cash already gone. In a first dividend year that produces three demands inside roughly twelve months: US tax in April, a UK balancing payment plus first payment on account the following January, and a second payment on account that July.

Where do things fall between the UK accountant and the US preparer?

Almost every failure here is a handoff failure rather than a technical one. These are the points at which each side assumes the other has it.

Payment dates. The UK accountant records which UK year a payment relates to; the US return needs the date the money left the founder's account. Both are true and only one is usually written down.
The company's own accounts, reconciled for Companies House and HMRC, with nobody asking whether the founder's ownership percentage makes them reportable on the personal FBAR.
Dividend timing, where declared and paid can sit in different months and, near a year end, in different tax years in both countries at once.
Director's loan account movements, which the UK accountant tracks closely and which nobody has been asked to look at from the US side.
Directors' benefits reported to HMRC, which arrive in UK-year format and have to be re-cut before they are usable.
Extension mechanics. The automatic two-month extension needs a statement attached to the return. That is the preparer's job, and it goes missing when the founder assumes the extension is entirely passive.
The paid or accrued choice, which no UK accountant will raise because it is a US filing position with no UK counterpart.

What does a properly scoped engagement cover, and what is wrongly assumed to be included?

In scope: a dated information request issued to the founder and the UK accountant in January, not a document chase in September.
In scope: the federal return with its international schedules, and the state return where a state connection persists.
In scope: the FBAR, prepared from an account list that includes company accounts attributed by ownership and accounts the founder only signs on.
In scope: the Form 1116 computation by category, with a documented position on the paid or accrued method and a tracked carryback and carryforward position.
In scope: extension filings with the required statement, tracked so the October date is not quietly missed while UK numbers are awaited.
In scope: a computed estimated tax schedule for the year ahead, produced alongside the return rather than after it.
In scope: a written reconciliation of UK figures to the US calendar year, so next year starts from a record rather than a reconstruction.

Wrongly assumed: that the UK accountant's Self Assessment work covers the US return. The two share almost no line items and no period.
Wrongly assumed: that a P60 is enough. It reports a UK year; the US return needs a calendar year.
Wrongly assumed: that extending buys enough time to wait for UK numbers. Even the discretionary December date arrives before the 31 January UK payment.
Wrongly assumed: that an extension to file postpones payment. It does not, and interest runs from the regular due date.
Wrongly assumed: that the FBAR travels with the return. It has its own due date and its own automatic extension.
Wrongly assumed: that catching up on unfiled prior years is part of the annual cycle. It is a separate remediation exercise.
Wrongly assumed: that the Form 5471 disclosure is the company's problem. It is filed with the founder's personal return, by the founder.

The founders who find this straightforward do not have simpler affairs. They are the ones whose personal US engagement runs on its own calendar, requests its own information in January, holds a documented position on the paid or accrued method, and treats the UK accountant as a source of dated facts rather than a substitute filer. All of it is preparation and compliance work, entirely doable on a schedule. It is only impossible when it starts in April.