Tax

6 min read

Self Assessment: what to prepare before 31 January

A calm, step-by-step list of the records your accountant needs, so your return is filed weeks before the deadline instead of on the night.

Tax forms and a pen laid out on a wooden desk

Written by

Eleanor Hart

Founding Partner

← All insights

Start with your income

Gather your P60 or final payslip for each job, any P11D for benefits, and statements for self-employed income, rent, dividends and savings interest. If you sold shares or property during the tax year, keep the purchase and sale documents together.

Then your expenses and reliefs

Keep a simple list of business costs with the receipts behind it. Add pension contributions you paid personally and any Gift Aid donations: both can reduce your bill, and both are easy to forget.

Check your payments on account

If your last bill was over £1,000, HMRC will usually ask for two advance payments towards the next one. We check whether they still make sense and, where your income has fallen, ask HMRC to reduce them.

Send it early

A return sent in October gives you three months to plan the payment. A return sent in January gives you three days. The work is the same; the stress is not.

§ NEXT STEP

Have a question these notes don't answer?

Book a free call →

STUDIO

12 Market Street, London EC2A 4XX

HOURS

Mon–Fri, 9:00–18:00

© 2026 Countwell. All rights reserved.

Countwell

STUDIO

12 Market Street, London EC2A 4XX

HOURS

Mon–Fri, 9:00–18:00

© 2026 Countwell. All rights reserved.

Countwell

STUDIO

12 Market Street, London EC2A 4XX

HOURS

Mon–Fri, 9:00–18:00

© 2026 Countwell. All rights reserved.

Countwell

Create a free website with Framer, the website builder loved by startups, designers and agencies.