What documents do I need to file my tax return? (2026/27 Guide)

To strictly comply with UK tax law, you must support your Self Assessment with accurate evidence. Under section 8 of the Taxes Management Act 1970 (TMA 1970), HMRC holds the legal authority to require you to deliver such accounts, statements, and documents as may reasonably be required to establish your tax charge.

For the 2026/27 tax year, what constitutes a “document” is undergoing a statutory transformation. While traditional paperwork remains for some income sources, the government now mandates digital record-keeping for others.

Below is an exhaustive breakdown answering the core question—what documents do I need to file my tax return—categorised by your specific income sources.

Traditional Income Documents (Employment, Investment, and Pension)

If you receive income outside of a self-employed business, you must gather traditional physical or PDF documents to prove your earnings and any tax already deducted at source.

Employment and Pension Income

For individuals receiving a salary or company benefits, you must extract the necessary figures from official payroll documents. Essential documents typically include your P60 (end-of-year pay and tax summary), your P45 (if you left a job during the tax year), and your P11D (which details benefits in kind, such as company cars or medical insurance).

Similarly, if you draw pension income, you must obtain a P60P from your pension provider and notify HMRC of your State Pension receipts, ensuring all pension income is accurately reflected.

Investment Income

If you receive income from investments, you must secure dividend vouchers from the companies you hold shares in, as well as interest certificates from your banks or building societies.  These documents prove the exact amount of investment income received during the tax year.

Cryptoasset Transaction Records

If you trade, stake, or dispose of cryptoassets, you must maintain a rigorous audit trail for Capital Gains Tax or Income Tax purposes. Cryptoasset exchanges often only keep records for a short period, placing the onus entirely on you to keep your own records for every transaction.

Your crypto documentation must detail the type of cryptoasset, the transaction dates, the buy/sell units, the value of the transaction in GBP, your cumulative totals, and the relevant wallet addresses.

“A link to an open source blockchain transaction and acknowledgement of the individual owning the public key involved in the transaction [should also be kept and produced for an enquiry].”

The 2026/27 Shift: Making Tax Digital (MTD) for ITSA

If you generate income from self-employment or property, the 2026/27 tax year fundamentally changes what documents you need.

From 6 April 2026, if your total qualifying income from self-employment and property exceeds £50,000, you are mandated to use Making Tax Digital for Income Tax Self Assessment (MTD for ITSA).

Digital Records (No Paper Summaries)

You can no longer rely on paper receipts and annual spreadsheets. You must create and store digital records of your self-employment and property income and expenses using MTD-compatible software.  For every transaction, your digital records must capture:

• The exact amount.
• The date the income was received or the expense was incurred.
• The category of the transaction (mirroring the standard Self Assessment categories).

Quarterly Updates

Instead of filing one annual document, your software will compile your digital records and send them to HMRC as a quarterly update.  For the 2026/27 tax year, you must strictly meet the following update deadlines:

• 7 August 2026
• 7 November 2026
• 7 February 2027
• 7 May 2027

Identity Verification and Simple Assessment

Before you can file these documents online, you must prove your identity. To deliver your return, you must complete the identity verification process via the GOV.UK One Login system, which securely validates your status before granting access to HMRC services.

Additionally, if HMRC decides they hold enough information to calculate your tax liability automatically, they may withdraw your notice to file a return and issue a Simple Assessment instead. If this happens, you must actively notify HMRC of chargeability if you have any other income or gains that are not included in that Simple Assessment calculation.

Record Retention Rules

Once you have filed your return, section 12B of the TMA 1970 strictly dictates how long you must keep these documents.

• Business and Property Records: If you carry on a trade, profession, or business (including letting property), you must retain your records until the fifth anniversary of the 31 January following the tax year.  (For example, 2026/27 business records must be kept until 31 January 2033).
• Personal Records: If your return only includes non-business income (like a salary or bank interest), you must keep the documents until the first anniversary of the 31 January following the tax year.

Failure to maintain or produce these records during an HMRC enquiry can lead to severe penalties.

Summary Table: Required Documents and Rules (2026/27)

Next steps for research: Audit all sole trader and landlord clients to determine whose combined gross income breaches the £50,000 threshold, and immediately transition their record-keeping to MTD-compatible software before the 6 April 2026 mandation date.