The deadline for online Self Assessment is January 31. If you miss it, HMRC charges a £100 penalty immediately, with additional penalties for further delays. Gathering your documents now gives you time to file accurately and avoid late-filing stress.

This checklist covers every document you need for the 2025/26 tax year (April 6, 2025 to April 5, 2026), organised by income type.

Employment income documents

Tick off each item as you collect it:

P60: Your employer must provide this by May 31. It shows your total pay and tax deducted for the tax year. If you had multiple jobs, get a P60 from each employer.

P45: If you left a job during the tax year, your former employer issued a P45. Keep all copies.

P11D: If you received benefits in kind (company car, private medical insurance, interest-free loans), your employer sends a P11D by July 6. This shows the taxable value of those benefits.

Payslips: Useful to cross-check your P60 figures, especially if you had irregular pay or bonuses.

Self-employment records

If you are self-employed or run a sole trader business:

Sales invoices: Every invoice you issued, showing income received.

Bank statements: For all business accounts, showing income and expenses. Highlight business transactions to separate them from personal spending.

Purchase receipts: Keep receipts for allowable expenses (stock, equipment, travel, office costs, professional fees). HMRC may ask for proof.

Mileage log: If claiming vehicle expenses using the simplified mileage rate (45p per mile for the first 10,000 miles), record every business journey with date, destination, and mileage.

Home office costs: If working from home, gather utility bills and mortgage interest or rent statements to calculate the proportion used for business.

Savings and investment income

Bank interest certificates: Your bank or building society sends an annual certificate showing gross interest earned. This applies to savings accounts outside an ISA.

Dividend vouchers: Statements from your broker or investment platform showing dividends received from shares or funds held outside an ISA.

Stocks and Shares ISA statements: Interest and dividends inside an ISA are tax-free, so you do not report them. Keep these separate to avoid double-counting.

Rental income

If you let out property:

Rental statements: Total rent received from tenants for the tax year.

Mortgage interest statements: You can claim relief on mortgage interest for rental properties, though the rules changed in recent years. Your lender provides an annual statement.

Letting expenses: Receipts for repairs, maintenance, letting agent fees, insurance, and landlord safety certificates (gas, electrical, EPC).

Capital gains

If you sold assets (shares, property, or valuable items worth more than £6,000):

Sale documents: Contract notes showing the sale price and date.

Read also: UK Capital Gains Tax on Investments: What Every Investor Must Know

Purchase documents: Original purchase price and date, including any associated costs (stamp duty, solicitor fees, renovation costs for property).

Transaction costs: Broker fees or auctioneer commission paid on the sale.

The annual Capital Gains Tax allowance is £3,000 for 2025/26 (as of September 2026, verify current rates with HMRC). You only pay tax on gains above this threshold.

Pension contributions

Pension statements: If you made personal pension contributions to a SIPP or private pension, your provider sends an annual statement. You can claim higher-rate or additional-rate tax relief through Self Assessment.

Workplace pension confirmation: Your P60 or payslips show pension contributions deducted by your employer. These are usually dealt with automatically, but check if you made additional contributions outside your payslip.

Charitable donations and Gift Aid

Gift Aid receipts: If you made donations under Gift Aid to UK-registered charities, you can extend your basic-rate band. The charity claims the basic-rate relief, but you claim the difference if you pay higher-rate or additional-rate tax.

Keep a record of the charity name, donation amount, and date.

Student loan information

If you have a student loan and earned above the repayment threshold, your employer deducted repayments through PAYE. Your P60 shows this. If you are self-employed or have other income, HMRC uses your Self Assessment return to calculate the amount due.

Check which plan you are on (Plan 1, Plan 2, Plan 4, or Postgraduate Loan) and the current repayment threshold on the GOV.UK website.

Other income sources

Tick off any that apply:

State benefits: If you received taxable benefits (such as Jobseeker’s Allowance or contribution-based Employment and Support Allowance), you need the total received. Some benefits are tax-free (such as Personal Independence Payment).

Foreign income: If you received income from overseas (rental income, dividends, employment), gather statements and conversion rates to GBP.

Taxable grants or payments: Some grants (including certain COVID-19 support payments in earlier years) were taxable. Check your records.

Organising your documents

Once you have gathered everything, organise by category. A simple folder (physical or digital) labelled by income type makes filing easier. Scan paper documents and save them as PDFs with clear filenames (for example, P60-2026.pdf, Rental-Income-2026.pdf).

As covered in foundational texts such as Principles of Finance, accurate record-keeping is a core discipline of personal financial management, and tax compliance is one area where it directly affects your obligations and potential penalties.

Cross-check figures before entering them into your tax return. If a number looks unusual (such as a suspiciously low or high figure), double-check the source document.

What to do next

Once you have your documents:

  1. Log in to your Self Assessment account on GOV.UK or set one up if you have not registered yet.
  2. Work through each section of the online form, entering figures from your documents.
  3. The system calculates your tax liability automatically.
  4. Submit before January 31 to avoid penalties.

If your tax bill is below £3,000 and you have a PAYE job, you can ask HMRC to collect it through your tax code over the next year instead of paying a lump sum.

According to HMRC, late filing after January 31 results in an immediate £100 penalty, with daily penalties of £10 (up to £900) starting after three months, and further percentage-based penalties after six and twelve months (HMRC, 2026).

This is general educational guidance on gathering Self Assessment documents. Tax rules and allowances change each year. For advice specific to your circumstances, consult an FCA-authorised financial adviser or a qualified accountant. Nexzoe is not authorised by the FCA to provide regulated financial advice.