Client Portal

Your documents, handled the way tax records should be

How your documents are handled

Documents are held by Supabase on our behalf, in the United Kingdom, with two-factor sign-in required on every account. Full detail is in our privacy policy.

Encrypted in transit and at rest

Documents travel over encrypted connections and are stored encrypted. Download links are time-limited and tied to your account, never an open link.

Access limited to your engagement

Only the people working on your return can open your documents. Every upload and download is logged, and the log is kept as part of our records.

A checklist per return, not a folder

The US and UK tax years do not line up, so each document records the period it covers and the returns it feeds. One P60 can serve both filings without being uploaded twice.

Kept only as long as required

Documents are kept for 6 years after the engagement ends, as professional and record-keeping rules require, then deleted.

What we will ask you for

Pick the description that fits you. Dual filers see one combined list, not two: documents that feed both returns are asked for once.

Tell us what applies to you

A few answers cut the list down to what you actually need to find.

Up to 27 documents may apply, of which 8 are needed before we can start. Almost nobody needs all of them — answer a few questions above to narrow it.

Identity and onboarding

Photo identificationNeeded to start
Passport or driving licence, in date.
Proof of addressNeeded to start
A utility bill or bank statement from the last three months.
Tax reference numbersNeeded to start
US Social Security or ITIN, and UK UTR and National Insurance number.
Send these through the portal only. Never by email — it is not a secure channel for identifying numbers.

Employment and income

Form W-2Needed to start
Wage and tax statement from a US employer, one per employer.
Form 1099-NEC or 1099-MISC
Payments received as a contractor or for services.
Form P60Needed to start
End-of-year certificate from your UK employer, issued after 5 April.
Form P45
Issued when you leave a UK job. Needed for any employment that ended in the year.
Form P11D
Benefits in kind — company car, medical insurance, interest-free loans.

Savings and investments

Forms 1099-INT and 1099-DIV
Interest and dividends from US accounts.
Form 1099-B or brokerage composite
Sales of shares or funds. The full composite statement, not the summary page.
Schedule K-1
Your share of income from a partnership, S-corporation or trust.
Bank and building society interest certificates
Interest credited in the year, per account. Banks issue these on request.
Dividend vouchers
Dividends from UK companies, including your own if you are a director.
ISA and fund holdings
Statements for any ISA or UK-domiciled fund, including what is held inside it.
Funds held inside an ISA can be PFICs for US purposes, which changes how they are taxed and reported. We need the holdings, not just the wrapper's value.

Property

Form 1098
Mortgage interest paid on a US property.
Rental income and expenses
Letting agent statements, or your own record of rent received and costs paid.
The US and UK compute rental profit differently — US depreciation is mandatory — so send the underlying figures rather than a finished profit number.
UK mortgage interest statement
Annual statement for any mortgage on a let property.
Completion statement for any property sold
Plus the original purchase completion statement and costs of improvement.

Pensions and giving

Pension contribution certificate
Contributions to a workplace or personal pension in the year.
Gift Aid record
Charitable donations made under Gift Aid.

Foreign accounts and reporting

Foreign account list with peak balancesNeeded to start
Every non-US account: institution, account number, and the HIGHEST balance it reached at any point in the year.
The FBAR asks for the highest balance during the year, not the closing balance. A year-end statement is not enough. Include accounts you only sign on, and joint accounts at their full value.
Certificates of foreign tax paid
Evidence of tax already paid in the other country, used to claim credit.

Residence and travel

Record of days in each country
Dates of arrival and departure for the year. A calendar export or travel history is fine.
Both the UK Statutory Residence Test and the US substantial presence test count days, and they count them differently. Approximate dates are not sufficient.

Previous returns and payments

Record of estimated tax payments
Dates and amounts of any quarterly payments made to the IRS.
Last year's Form 1040Needed to start
The complete return as filed, including all schedules.
Last year's SA302 or filed returnNeeded to start
The tax calculation for the previous year, from HMRC or your last adviser.
Student loan plan type
Plan 1, 2, 4, 5 or postgraduate. Shown on your payslip or in your SLC account.

Dates we work back from

31 January — UK Self Assessment, online Balancing payment and first payment on account fall due the same day.
15 April — US federal return Automatic extension to 15 June for filers living abroad; to 15 October on request.
31 July — UK second payment on account
15 October — US federal return, extended
15 October — FBAR Due 15 April with an automatic extension to 15 October that needs no request.

Want this list narrowed to your situation and emailed to you?

Build my checklist

Not sure which documents apply to you?

Tell us where you live, what you hold and which years are outstanding. We will say what applies and what it involves before any work begins.