Introduction: The Expat Tax Consultation Checklist That Starts With Two Tax Years
A useful expat tax consultation checklist begins with one awkward fact: Britain and America measure the year differently. HMRC runs from 6 April to 5 April. The IRS runs from 1 January to 31 December. Consequently, no single British document ever lines up with a US return, and no single American form ever satisfies HMRC.
Most published checklists ignore this entirely. They list a W-2, a 1099 and a passport, then stop. For a high-net-worth American in London, that list is close to useless. Your income arrives through PAYE, and your investments sit in an ISA or a general investment account. Meanwhile, the bonus lands in March, straddling two American tax years at once.
At TaxYork we prepare both returns for wealthy individuals, company owners and investment professionals across the City. Therefore, we know precisely which records make a preparation engagement fast and accurate, and which omissions cost clients thousands. This guide sets out the documents we ask for, why each one matters, and where the two systems collide.
What the Expat Tax Consultation Checklist Covers Before Anything Else
Preparation work fails on missing history far more often than on missing arithmetic. Furthermore, the records hardest to recover are the ones nobody thinks to keep.
The Expat Tax Consultation Checklist Starts With Identity and Prior Filings
Bring your Social Security number or ITIN, your Unique Taxpayer Reference, and your National Insurance number. Additionally, bring the last three US federal returns and the last three Self Assessment returns. We read prior returns for carryforwards, not for nostalgia.
Unused foreign tax credits carry forward for ten years under the rules governing Form 1116. Consequently, a client who arrives without prior returns often forfeits credits already earned. We also need any state return filed before you left America, because several states pursue former residents long after departure.
Why Three Years of History Is the Minimum
Elections made years ago still bind you. A section 6013(g) election, a mark-to-market election on a fund, or an accrual election for foreign taxes all survive indefinitely. Therefore, we must see the year in which each election first appeared.
The UK Records HMRC Will Not Keep For You
Your IRS online account holds transcripts for roughly ten years. By contrast, your HMRC personal tax account typically displays only about five. Consequently, older UK figures must come from your files, your employer, or HM Revenue and Customs direct.
Download and save every year now, while access is straightforward. Clients who wait until an enquiry lands rarely enjoy the same convenience.
Employment Records: The P60 That Covers the Wrong Twelve Months
British payroll paperwork is excellent. Unfortunately, it answers a question the IRS never asked.
Your P60 Straddles Two American Tax Years
A P60 reports pay and tax for 6 April to 5 April. Your 2025 US return, however, needs 1 January to 31 December 2025. Therefore, we cannot simply copy a P60 total onto Form 1040.
Instead, we need your monthly payslips for the whole calendar year. Each payslip shows gross pay, PAYE deducted and National Insurance for that month. Accordingly, we can rebuild an exact calendar-year figure rather than estimating one. Bring payslips for the year either side of any bonus, promotion or job change.
P11D, Coding Notices and Benefits Britain Taxes Differently
Your P11D reports benefits in kind: private medical cover, a company car, interest-free loans. America taxes several of these differently, and some are not taxable at all on a US return. Bring the form, along with your PAYE coding notice for each year.
Payrolling of benefits becomes mandatory in phases from 6 April 2027, with employment-related loans and living accommodation remaining voluntary. Meanwhile, the P11D still governs. If your employer operates a PAYE Settlement Agreement, tell us immediately. Under such an agreement the employer bears the UK tax. Consequently, you have no foreign tax credit to claim on that income.
Redundancy, Termination and Share-Based Pay
Bring settlement agreements, termination statements and any restrictive covenant payment schedule. Britain and America split such payments differently, and the paperwork decides the answer.
Foreign Account Records: The FBAR Peak Balance Nobody Reconstructs Later
This section causes more remedial work than any other. Moreover, it is where penalties concentrate.
Every Account, Every Peak, Every Currency
The FBAR requires the maximum balance in each foreign account during the calendar year, not the year-end balance. Consequently, a statement showing 31 December is insufficient. We need twelve months of statements for every account you hold, sign for, or control.
Bring the institution name, address, account number and peak balance for each. Include current accounts, savings accounts, cash ISAs, stocks and shares ISAs, SIPPs, workplace pensions, offshore bonds and joint accounts. Aggregate balances above $10,000 at any moment trigger the filing, as the IRS FBAR guidance confirms.
Federal regulations at 31 CFR 1010.430 require you to retain those records for five years. However, the FBAR itself reaches back six years under its own limitation period. Therefore, keep six years, not five.
Which UK Accounts Count and Which Do Not
Cash ISAs and stocks and shares ISAs are reportable. So are SIPPs and most workplace pensions. Crypto held directly in a wallet, by contrast, still falls outside the FBAR definition. Exchange accounts holding fiat currency, however, are reportable. Furthermore, brokers now issue Form 1099-DA for digital asset sales, so bring those too.
Since 16 July 2025 the duty to self-certify tax residence sits with you, the account holder, rather than the bank. Accordingly, keep copies of every certification form you sign.
Signature Authority and the Extension Running to April 2027
If you sign on employer accounts without owning them, you hold signature authority. FinCEN has repeatedly extended the deadline for certain employees and officers of investment advisers. The latest extension runs to 15 April 2027. Consequently, many bankers and fund professionals in London have a live obligation nobody has mentioned to them. Bring a list of every corporate account you can sign on.
Form 8938 Runs on Entirely Different Thresholds
Form 8938 is not the FBAR. Living abroad and filing jointly, you report when specified foreign assets exceed $400,000 at year end. The any-time threshold is $600,000. Filing separately, those figures halve to $200,000 and $300,000. The FATCA summary sets out each combination. Notably, a non-US spouse makes the threshold worse, not better.
Investment, Pension and Share Scheme Paperwork
Wealthy clients lose the most value in this section, because British products behave badly under American rules.
PFIC Statements Your UK Platform Will Not Volunteer
Almost every UK OEIC, unit trust, investment trust and exchange-traded fund is a passive foreign investment company. Each holding needs its own Form 8621. Without a qualified electing fund annual information statement, the punitive excess distribution regime applies instead.
Therefore, bring your consolidated tax certificate, your full transaction history and any QEF statement your platform provides. Most British platforms provide none. Ask anyway, in writing, and keep the reply.
Pension Statements and What the Treaty Actually Needs
Bring annual benefit statements for every UK pension, including deferred schemes from former employers. Additionally, bring evidence of employer contributions, member contributions and any pension input amount above the annual allowance. Where an annual allowance charge arises, bring the scheme pays election, because the timing affects both returns.
Share Schemes: Section 431 Elections, ERS Certificates and Vesting Schedules
British share plans generate paperwork with short fuses. A section 431 election must be made within fourteen days of acquisition. An American section 83(b) election allows thirty days. Consequently, the two deadlines rarely coincide, and a missed election cannot be repaired.
Bring option grant letters, vesting schedules, exercise notices and section 431 elections. Add your employer's annual return under the employment-related securities rules. We use these to fix your US cost basis, which determines every future gain.
Business, Property and Self-Employment Records
Company Owners and Directors
Bring statutory accounts, corporation tax computations, dividend vouchers and your director's loan account balance at each year end. An overdrawn loan account can create a deemed dividend under US rules, so the balance genuinely matters.
Owners of UK companies also face Form 5471 and, in many cases, Form 8992. Notably, a nil or negative inclusion still requires the form to be filed.
Rental Property in Britain or America
Bring rental statements, letting agent summaries, mortgage interest certificates and evidence of capital improvements. If you let UK property while living abroad, bring your approval under the non-resident landlord scheme. Britain and America compute rental profit differently, particularly on interest relief and depreciation, so raw figures beat summaries every time.
Self-Employment and the Certificate of Coverage
Self-employed clients should bring a certificate of coverage issued under the US-UK social security agreement. That single document removes the 15.3% American self-employment charge where you pay National Insurance instead. Furthermore, Making Tax Digital for Income Tax became mandatory from 6 April 2026 above £50,000 of qualifying income. Therefore, bring digital records rather than a shoebox.
Exchange Rates, Payment Evidence and the Foreign Tax Credit File
Two Official Rates Doing Two Different Jobs
Income converts at the IRS yearly average rate, which stood at 0.759 pounds to the dollar for 2025. Account balances for FBAR and Form 8938 convert at the Treasury year-end rate instead. The Treasury reporting rates of exchange put that figure at 0.743 for 31 December 2025.
Those two rates sit 2.15% apart. On a £310,000 balance the difference is $8,795. Therefore, mixing them produces a wrong FBAR, and consistency matters more than convenience.
Proving the UK Tax You Actually Paid
A foreign tax credit needs evidence of payment, not merely of liability. Accordingly, bring your Self Assessment statements of account, your payment receipts and the dates money left your bank. Payments on account distort this badly. Two instalments plus a balancing payment can push almost two years of British tax into one American year.
The cash basis is the default. An accrual election under section 905(a) can smooth the mismatch. However, that election is irrevocable, so we discuss it first. See the Self Assessment deadlines for the payment dates that drive the timing.
When Your UK Return Changes Later
If HMRC amends your liability after we file, section 905(c) requires a notification to the IRS. That obligation is mandatory rather than optional. Meanwhile, amended returns claiming foreign tax credits enjoy a ten-year window, which is far longer than the ordinary three years. Consequently, old years remain fixable, provided the paperwork survives.
What Changes When You Are Behind on Filings
Some clients arrive with several unfiled years. That situation is common and entirely fixable, but it changes the document list.
Six Years of Accounts, Several Years of Returns
Bring six years of account statements with peak balances, and income records for every unfiled year. Additionally, bring evidence of what you understood at the time: correspondence with a bank, an accountant, or a former employer. Our FBAR and FATCA compliance team uses that evidence to establish the facts precisely.
Why Contemporaneous Evidence Carries the Argument
A non-wilful position rests on narrative, not assertion. Therefore, dated emails, engagement letters and bank correspondence matter enormously. Clients who bring them resolve matters faster and on better terms through our catch-up filing service.
A Worked Case Study: A London Portfolio Manager's First Meeting
A dual American-British portfolio manager came to us in September 2026. He earned £318,000 in calendar year 2025 and had never filed an FBAR correctly.
What He Brought, and What He Had Missed
He arrived with a single P60 for 2025/26 and year-end statements for four accounts. That P60 covered April 2025 to April 2026, so it captured only nine months of the year we needed. We therefore requested twelve months of payslips. Those produced an exact £318,000, or $418,972 at the 2025 average rate of 0.759.
His PAYE for the calendar year came to £131,000, worth $172,595. Against US tax of $121,300, that generated a carryforward of $51,295 available for ten years.
The Peak Balance That Changed Everything
His sweep account showed £42,000 on 31 December. However, his March bonus had pushed it to £310,000 for four days before he moved the money. At the Treasury rate of 0.743, that peak converted to $417,227. Reporting the year-end figure alone would have understated the FBAR by more than $370,000.
We also identified nine reportable accounts rather than four. ISAs, his SIPP and two employer accounts he could sign on all counted. Non-wilful penalties can reach $16,536 per account per year. Across nine accounts, the single-year exposure approached $148,824.
The Documents That Saved Him Money
Two UK funds in his general investment account, worth £96,000, were PFICs requiring separate filings. Furthermore, an old email held his section 431 election from 2022. That document established a US cost basis, removing roughly $38,000 of phantom gain on shares sold in 2025. That one document justified the entire engagement fee several times over.
How TaxYork Can Help
We prepare US and UK returns together, in one engagement, for high-net-worth individuals, founders and investment professionals. Our team handles US tax returns for Americans abroad, Self Assessment, FBAR, Form 8938, PFIC computations and share scheme reporting.
Furthermore, we turn your expat tax consultation checklist into a permanent client file. Consequently, the second year takes a fraction of the effort. Where treaty positions or elections improve the outcome, our treaty and foreign tax credit specialists apply them correctly. Clients moving between countries can also draw on our cross-border planning support.
Conclusion
A thorough expat tax consultation checklist saves money because it prevents estimates. Payslips beat a P60. Monthly statements beat a year-end balance. Original elections beat recollection.
Gather the records before your first meeting, and the preparation work becomes straightforward. Leave them behind, and every figure becomes an approximation that the IRS or HMRC may later question. Ultimately, the quality of your documents determines the quality of your return.
Contact Us
Ready to start? Send your documents to hello@taxyork.com or call 020 3488 8606 to discuss your position. Alternatively, book a consultation and we will send you a tailored document request within one working day.
Disclaimer
This article provides general information only and does not constitute tax advice. Tax rules change frequently, and their application depends on individual circumstances. You should obtain professional advice tailored to your position before acting. TaxYork accepts no liability for any action taken in reliance on this article. Professional guidance is available from ICAEW, the Chartered Institute of Taxation, the AICPA and MoneyHelper. Further official guidance appears in IRS Publication 54 and the IRS guide for US citizens and resident aliens abroad.