Can my UK accountant prepare my IRS streamlined submission?

Only if they are also equipped to prepare US returns. The IRS requires anyone who prepares or assists in preparing federal tax returns for compensation to hold a valid PTIN, and the submission involves US-law computations that differ from UK ones. Most clients keep their UK accountant for Self Assessment and company accounts and use a separate US preparer who works from the UK accountant's records.

Which UK documents does a US preparer need for a streamlined filing?

The core set is the SA100 returns with all supplementary pages, SA302 tax calculations, HMRC statements showing dates of tax paid, capital gains computations with full share pool histories, dividend vouchers, pension statements and, for company owners, full accounts, the CT600 and the director's loan account. Because three US calendar years overlap four UK tax years, four years of UK returns are needed.

Why is my US capital gain different from the gain on my UK return?

The UK matches share sales to same-day and following-30-day purchases and then to a Section 104 pool at average cost, as HMRC helpsheet HS284 explains. The US tracks basis by lot and generally treats the earliest shares as sold first unless specific shares are identified. Cost and proceeds are also translated into dollars at the rates for their own dates, so the two gains rarely agree.

Can my accountant sign Form 14653 for me?

No. Form 14653 is the taxpayer's own certification that they are eligible for the Streamlined Foreign Offshore Procedures, have filed all required FBARs, and failed to comply through non-willful conduct. It concerns your personal knowledge and conduct, so neither a UK accountant nor a US preparer can sign it. The IRS processes returns without the favourable terms if the certification is incomplete or deficient.

How long do I have to amend a UK Self Assessment return?

GOV.UK states that a Self Assessment return can be corrected within 12 months of the Self Assessment deadline; for the 2024 to 2025 tax year that usually means by 31 January 2027. After that you must write to HMRC to report undeclared income, or claim overpayment relief, which is available up to 4 years after the end of the tax year concerned.

What is the difference between Form 2848 and Form 8821?

Form 2848 authorises an individual who is eligible to practise before the IRS to represent you. Form 8821 authorises any designated individual or firm to inspect or receive your confidential tax information for the tax types and periods listed, which is an information authorisation only. A UK accountant who is not eligible to practise before the IRS could be named on Form 8821 but not appointed on Form 2848.

IRS Streamlined Filing Experts and Your UK Accountant

IRS Streamlined Filing Experts do not replace your UK accountant; they take the UK accountant's figures, rebuild them under US rules, and take responsibility for the US submission. The two professionals do separate jobs on the same set of facts. Your UK accountant prepares the Self Assessment return and the company accounts under UK law. The US preparer produces the delinquent or amended US returns, the FBARs and the information returns under US law. The work goes smoothly when the UK accountant is asked for the right documents at the outset, and it goes wrong when UK totals are copied straight onto US forms.

Most of the streamlined submissions we prepare are for people with substantial UK affairs: director-shareholders of UK companies, bankers with deferred pay and share awards, and investors with long-held portfolios. Almost all have a UK accountant of many years' standing. This guide sets out what we ask that accountant for, where UK numbers must be reworked, who authorises and signs what, and what to do when the US work reveals a UK mistake.

What do IRS Streamlined Filing Experts need from your UK accountant?

The Streamlined Foreign Offshore Procedures are an IRS route that lets eligible taxpayers living outside the United States file overdue or corrected US returns and FBARs without the penalties that would normally apply, provided their earlier failures were non-willful. The IRS sets out the terms at irs.gov/individuals/international-taxpayers/u-s-taxpayers-residing-outside-the-united-states. The submission covers the three most recent tax years for which the US due date has passed, together with all required information returns for those years, and FBARs for the six most recent years for which the FBAR due date has passed. The full tax and statutory interest must be sent with the returns. For a US citizen or green card holder, the non-residency test is met by having no US abode and being physically outside the United States for at least 330 full days in at least one of those three years.

Almost all of the evidence for those three years of worldwide income already sits in your UK accountant's files. Because the UK tax year does not match the calendar year, three US years overlap four UK tax years, so we ask for four years of UK returns, with the underlying workings. This is the request list we hand to the UK accountant at the start of an engagement.

SA100 tax returns for every UK tax year that overlaps the three US years, with all supplementary pages filed: employment, self-employment, partnership, UK property, foreign, capital gains and residence pages.
SA302 tax calculations for the same years, plus the HMRC tax year overviews or statements of account showing the date and amount of every payment of UK tax, including payments on account and any repayments.
Capital gains computations for every disposal, together with the full Section 104 pool history for each shareholding: every acquisition date, quantity and cost, for holdings still owned as well as those sold.
Dividend vouchers, interest certificates and consolidated tax certificates from investment managers, showing payment dates and gross amounts.
For any company you own or control: full statutory accounts, the detailed profit and loss account, trial balance, CT600 and corporation tax computation, share register, dividend minutes and the director's loan account ledger, for every accounting period ending in the US years.
Employment records: P60s, P11Ds, payslips where pay was irregular, and vesting or exercise statements for share awards and deferred pay.
Pension statements showing employee and employer contributions, year-end values and any amounts drawn.
Rental income and expense schedules for each let property, with purchase dates and costs.
Working papers behind any residence, treaty or foreign income position taken on the UK return.
Copies of HMRC enquiries, amendments and correspondence for the years concerned.

Some items will not be in the UK accountant's file because a UK return never needed them: statements for ISAs and other UK tax-exempt accounts, and the highest balance on each account in each calendar year, which the FBAR requires. Those come from you and your banks.

Why can't the US preparer simply copy the figures from my Self Assessment return?

A Self Assessment return is an accurate statement of your income under UK law for a UK tax year. A US return needs your income under US law for a calendar year, expressed in US dollars. Four structural differences mean that the same underlying facts produce different numbers, and each one has to be reworked from source documents.

The first is the period. The UK tax year begins in early April, so each US calendar year takes roughly three months from one UK tax year and nine months from the next. Salary can usually be re-cut from payslips. Dividends, interest, bonuses and capital disposals have to be allocated by their actual dates. This is why we ask for dated vouchers and transaction-level schedules rather than the annual totals on the SA100. A bonus paid in March and a share sale in February both fall into a different US year from the one a quick reading of the UK return would suggest.

The second is share identification. HMRC's helpsheet HS284, published at gov.uk/government/publications/shares-and-capital-gains-tax-hs284-self-assessment-helpsheet, explains that shares sold are matched first with shares acquired on the same day, then with shares acquired in the following 30 days, and then with the Section 104 holding, in which every share is treated as acquired at the same average cost. The United States does not pool ordinary shares in this way. US basis is tracked by lot, and where specific shares are not adequately identified the earliest-acquired shares are generally treated as sold first. A UK computation built on average pool cost therefore cannot be used as the US gain, even before currency is considered.

The third is the list of items that are exempt in the UK but taxable in the US. Interest, dividends and gains inside an ISA do not appear on a UK return at all, yet a US citizen must report them. The same is true of premium bond prizes and of certain receipts that the UK treats as wholly or partly tax-free, such as the tax-free element of a pension lump sum, where the US treatment depends on a careful reading of the treaty and should never be assumed to follow the UK result. A gain on a main home that is fully relieved in the UK may be only partly excluded in the US. Because none of these items is on the SA100, a US return built from the SA100 will understate income.

The fourth is funds. Many UK and other non-US collective investment funds, including OEICs and exchange-traded funds, are passive foreign investment companies for US purposes. The IRS explains at irs.gov/forms-pubs/about-form-8621 that Form 8621 is filed by a US person who is a direct or indirect shareholder of a PFIC in situations that include receiving certain distributions, recognising gain on a disposal, and reporting elections. The UK return shows a dividend and perhaps a capital gain. The US return may need a separate Form 8621 for each fund, with a different computation of income. We need the fund names, identifiers, purchase history and year-end values from the investment manager, and the UK accountant's dividend schedule is the quickest index to what is held.

Beneath all four sits currency. Each sterling amount is translated into dollars at the rate for its own date, so a UK gain multiplied by a single exchange rate is not the US gain.

Worked illustration: one share sale, two different gains

The following figures are an illustration only, and the exchange rates are assumptions chosen to show the mechanics. A US citizen living in London bought 1,000 shares in a listed UK company in 2012 at 12 pounds each and a further 1,000 in 2021 at 48 pounds each. In February 2025 she sold 1,000 shares at 60 pounds each, for proceeds of 60,000 pounds. No specific lot was identified at the time of sale.

Her UK accountant applies the Section 104 rules. The pool holds 2,000 shares with a total cost of 60,000 pounds, an average of 30 pounds a share. The cost of the 1,000 shares sold is 30,000 pounds and the UK gain is 30,000 pounds, reported on the capital gains pages for the UK tax year that includes February 2025.

The US computation treats the 2012 shares as sold first. Assume a rate of 1.60 dollars to the pound at the 2012 purchase and 1.28 at the 2025 sale. US basis is 12,000 pounds at 1.60, or 19,200 dollars. US proceeds are 60,000 pounds at 1.28, or 76,800 dollars. The US gain is 57,600 dollars and it belongs on the 2025 US return. Had the UK gain simply been converted at the sale-date rate, the figure would have been 38,400 dollars, understating the US gain by 19,200 dollars and potentially placing it in the wrong year. The shares she still holds also differ: the UK pool carries them at 30 pounds each, while for US purposes they are the 2021 lot at 48 pounds each, translated at the 2021 rate. This is why we ask for the complete pool history, including holdings that have not been sold.

What does the US preparer need from UK company accounts for Form 5471?

Form 5471 is the US information return filed by certain US persons who are officers, directors or shareholders of foreign corporations, and the IRS lists it by name among the information returns that must accompany a streamlined submission. The form and its instructions are at irs.gov/forms-pubs/about-form-5471. For a client who owns a UK limited company, it is frequently the largest single piece of work in the submission, and it depends almost entirely on what the UK accountant can supply.

Filed statutory accounts are not enough on their own, particularly the abridged versions that small companies place on the public record. The form asks for an income statement and balance sheet in a US layout, earnings and profits under US tax principles, an analysis of share ownership, and a record of transactions between the company and its shareholders. An overdrawn loan account or a dividend voted but credited rather than paid looks routine in UK accounts and needs individual attention on the US form. Which category of filer you fall into depends on your ownership and role, and is settled before any numbers are entered.

Does my UK accountant have authority to share my records with a US preparer?

Two different permissions are often confused. The first is your accountant's authority to deal with HMRC as your agent. HMRC's guidance for agents at gov.uk/guidance/client-authorisation-an-overview makes the starting point clear: an agent must get authorisation from the client before acting on the client's behalf. That agent authorisation has traditionally been given on paper using form 64-8, and can also be given online, where the agent sends a request that the client accepts through their own HMRC sign-in, a process commonly called the digital handshake. The current mechanics should be checked on gov.uk, because HMRC has been moving agent services online.

The second permission is the one that matters for a streamlined submission, and HMRC agent authorisation does not supply it. Being authorised to speak to HMRC for you does not entitle your accountant to hand your returns, accounts and working papers to a third party. Your accountant owes you duties of confidentiality and holds your personal data, so releasing it to a US preparer requires your own clear instruction. In practice we ask clients to sign a short letter of authority addressed to the UK accountant that names the US preparer, lists the years and categories of document, and permits the two firms to speak directly. Most UK accountants welcome it, because it protects them and removes the client from the middle of every query.

Form 2848 or Form 8821: which US authorisation applies?

On the US side there are two forms and they do different things. The IRS states at irs.gov/forms-pubs/about-form-2848 that Form 2848 is used to authorise an individual to represent you before the IRS, and that the representative must be eligible to practise before the IRS. The IRS states at irs.gov/forms-pubs/about-form-8821 that Form 8821 authorises any individual, corporation, firm, organisation or partnership you designate to inspect or receive your confidential information for the tax types and periods listed.

The distinction matters in a two-accountant arrangement. Form 2848 suits the US preparer who will correspond with the IRS for you after the submission, provided that person is eligible to practise. Form 8821 is an information authorisation only and is not limited to people eligible to practise, so it is the form that could let a UK accountant see IRS information about you. Neither form is needed simply to file a streamlined submission.

Who is responsible for what in a streamlined submission?

Clear division of responsibility protects everyone, and it is worth agreeing in writing before work starts. In the engagements we run alongside a UK accountant, responsibility is divided as follows.

The UK accountant is responsible for the UK returns and accounts as filed, for supplying complete and accurate copies with their workings, and for preparing any UK amendment that proves necessary. They are not responsible for the US treatment of anything.
The US preparer is responsible for the US returns, information returns and computations, including every decision about how a UK item is treated under US law. The IRS states at irs.gov/tax-professionals/ptin-requirements-for-tax-return-preparers that anyone who prepares or assists in preparing federal tax returns for compensation must have a valid PTIN, and the paid preparer signs the returns and enters that PTIN on them.
The taxpayer is responsible for the completeness of the facts, signs each return under penalties of perjury, files or approves the FBARs, and personally signs the non-willfulness certification on Form 14653.
Both professionals are responsible for telling each other, with your permission, when one finds something that affects the other's return.

The certification deserves particular emphasis. Form 14653 is the statement on which a taxpayer living outside the United States certifies that they are eligible for the procedures, that all required FBARs have now been filed, and that the earlier failures resulted from non-willful conduct, which the IRS describes as conduct due to negligence, inadvertence or mistake, or a good faith misunderstanding of the law. It is your statement about your own knowledge and conduct, with the specific facts that explain it. No accountant in either country can sign it for you. The IRS warns that if the certification is incomplete or deficient, the returns are processed in the ordinary way without the favourable terms of the procedures.

The UK accountant still contributes something valuable here: factual chronology. Their file notes and engagement letters are often the best contemporaneous evidence of what you told them about your US citizenship and what was said about US filing. We draft the narrative from your account, check it against that record, and you read every word before signing.

What happens if the US work uncovers a mistake in my UK return?

It happens more often than clients expect, because a second professional is looking at every account for the first time. The discoveries we see most often are US-source dividends or interest from an old US account left off the UK foreign pages, a US rental property not reported in the UK, and foreign tax credit relief claimed in the UK for the wrong amount.

HMRC's time limits are set out at gov.uk/self-assessment-tax-returns/corrections. A Self Assessment return can be corrected within 12 months of the Self Assessment deadline, online or by sending a corrected paper return, and HMRC gives the example that a return for the 2024 to 2025 tax year would usually need to be changed by 31 January 2027. After that window closes, you must write to HMRC. For unreported income the letter states the tax year, why you think you underpaid and how much. For tax overpaid, overpayment relief can be claimed up to 4 years after the end of the tax year concerned. HMRC notes that the declaration on an overpayment relief claim must be signed by you and cannot be signed by a tax agent, which mirrors the position on the US certification.

A streamlined submission reaches back across four UK tax years, so some will usually be inside the 12-month amendment window and some outside it. We tell the UK accountant as soon as an item is identified, let them quantify the UK effect, and agree the order of filing. Both tax authorities should be told the same facts.

What if my UK accountant's past treatment conflicts with the US position?

This is the question that causes the most anxiety and the least needs to. A difference between the two returns is not in itself a problem. The useful discipline is to sort every difference into one of three kinds.

Differences of law. The UK pools shares and the US does not; the UK exempts ISA income and the US taxes it; the two countries measure a company's profit differently. Both returns are correct, and nothing needs to change on the UK side.
Differences of fact. The two returns show different dates, amounts, ownership percentages or residence histories for the same event. One of them is wrong, and it must be traced to source documents and corrected wherever the error lies.
Differences of judgement. The UK accountant characterised a payment from the company as a loan and the US analysis points towards a distribution, or a residence or treaty position was taken in the UK that sits awkwardly with the US filing. These need a conversation between the two professionals and a written note of the reasoning on each side.

In the third category the US preparer cannot simply adopt the UK view, because the US preparer signs the US return and must be satisfied with the position under US law. Nor can the US preparer rule on UK law. What works is a short technical call, with your consent, in which each explains their treatment. Where the positions remain incompatible, you decide, with both explanations in front of you, whether the UK return should be amended. The one outcome to avoid is a Form 14653 narrative that describes facts differently from the way they were presented to HMRC.

How should the two returns be timed so foreign tax credits line up?

For most UK residents with high income, the foreign tax credit is what prevents the same income being taxed twice, and it is claimed on Form 1116, described at irs.gov/forms-pubs/about-form-1116. The credit depends on UK income tax actually paid or accrued, matched to the right US year and category of income. UK tax for a given UK tax year is settled through payments that fall partly during that year and partly after it, so the UK tax relating to one US calendar year is paid across more than one US year. This is why we ask for HMRC statements showing payment dates and not only the SA302 liability.

The practical sequence we follow has three steps. First, the UK returns for all overlapping years are finalised, including any amendment prompted by the US review, so that the UK tax figures are settled. Second, the US returns are prepared from those final figures. Third, the complete package is assembled for posting, because the IRS requires streamlined returns and payments to be sent on paper to its Austin address and does not accept electronic submission, while the FBARs are filed electronically through FinCEN's BSA E-Filing System at bsaefiling.fincen.gov. If UK tax for one of the years changes after the US returns have been filed, the credit claimed in the US changes too, and the US return generally has to be revisited. Getting the UK side settled first avoids filing the US returns twice.

What should I do first?

Start by telling your UK accountant what is happening and why. Sign a letter of authority so the two firms can exchange documents directly, send the request list above, and gather the items only you hold: ISA and bank statements with highest balances, and records of any US accounts. Expect the US figures to differ from the UK figures. Our role is tax preparation and compliance: producing US returns that are accurate under US law and consistent, on the facts, with everything your UK accountant has already filed.