Self Assessment Checklist: What to Send Your Accountant

Don’t leave your tax return to the last minute

The hardest part of a tax return is often finding the paperwork. A missing statement, an unexplained payment or a forgotten income source can turn a straightforward job into a January scramble.

For the 2025/26 tax year, the online Self Assessment deadline is 31 January 2027. Any tax due must normally be paid by the same date. The tax year covers 6 April 2025 to 5 April 2026.

What should you prepare?

Not everything will apply to you, but start with:

• Your Unique Taxpayer Reference and National Insurance number.
• Business income and expense records.
• Relevant bank and credit card statements.
• Employment income details, including your P60 or P45.
• Rental income and property expense records.
• Details of savings interest, dividends and other income.
• Pension contribution and Gift Aid information.
• Details of assets sold that may need reporting.

If you’re self-employed, keeping clear income and expense records is a requirement—not just something that makes your accountant’s life easier.

Flag anything that changed

Started renting out a property? Taken a second job? Sold investments? Tell your accountant early, even if you’re unsure whether it matters.

It’s also worth separating business and personal transactions before sending your records over. A short explanation beside an unusual payment can save several follow-up emails.

Get the return done before the deadline gets close

Preparing early gives you time to resolve questions and understand what you owe. Filing earlier does not normally bring the standard January payment deadline forward.

Need help with your Self Assessment? Contact Taxlite in Birmingham to discuss your return and the records you need.