What Records Does an Accountant Need for Self Assessment?

Your accountant needs a complete picture of taxable income. That can include sole trader sales, employment income, pension income, rental income, dividends, bank interest, foreign income, capital gains, and any benefits in kind.

Expense claims need evidence and a business reason. Bank exports are useful, but receipts, invoices, mileage logs, software subscriptions, insurance documents, and home office calculations may also be needed.

Tell your accountant about asset sales, crypto transactions, overseas income, student loans, child benefit, pension contributions, charitable donations, and previous HMRC letters. These details can change the return materially.

List every source that existed during the tax year and mark each one complete, not applicable or outstanding. Include employments, pensions, sole trades, partnerships, UK and overseas property, interest, dividends, state benefits, gains, trusts and foreign income. A blank folder does not tell the accountant whether there was no income or the document was forgotten.

Record tax already deducted separately. P60, P45, P11D, CIS deduction statements, pension certificates and foreign withholding-tax evidence can materially change the calculation.

Provide the bookkeeping file or export, year-end bank and card statements, sales-platform statements, invoices, expense evidence, mileage records, stock information and details of assets bought or sold. Reconcile each balance and explain personal transactions or transfers between accounts.

Traditional accounting may require debtors, creditors, stock and work in progress even when cash has not moved. Cash-basis users still need evidence and year-end checks. Tell the accountant which method was used previously before changing it.

For property, create one schedule per property with rent, agent statements, repairs, finance costs, ownership and days unavailable. For investments and crypto, provide transaction-level acquisitions, disposals, fees and transfers between your own accounts—not only a gain figure from an app.

For overseas items, state the country, currency, date received, gross amount and foreign tax. Residence, remittance, treaty and exchange-rate questions can require specialist review, so identify them before the quote is agreed.

Create an issues list for missing statements, estimated private use, unreconciled balances, cash income, late invoices and positions that need advice. Keep estimates out of final totals until the accountant confirms how they should be treated.

If a document cannot be recovered, note what happened and provide alternative evidence. A transparent evidence gap can be assessed; an unexplained number cannot.

Use the accountant’s secure portal rather than ordinary email for identity and financial records. Agree file names and a cut-off date, then keep a copy of the final pack. Before submission, compare the return to that pack and confirm every issue has an answer.