If you need to file a Self Assessment return for the 2025/26 tax year, now is a useful time to get your records together. Preparing early gives you time to resolve missing information and budget for the payment due in January.
Know which deadline applies
For most taxpayers, the online filing deadline is 11:59pm on 31 January 2027. Any tax still owed for 2025/26 is normally payable by the same date. Paper returns generally need to reach HMRC by 31 October 2026. Different filing deadlines can apply in some cases, including where HMRC issues a later notice to file, so check your own notice.
See HMRC’s Self Assessment deadlines for the full rules. The 2025/26 return covers the tax year from 6 April 2025 to 5 April 2026.
Gather your records before you start
- Collect records for the income you need to report, such as self-employment, employment, rental income and investments.
- Reconcile business income with invoices and bank statements, and organise receipts for expenses you intend to claim.
- Keep details of pension contributions, Gift Aid donations and tax already deducted where relevant.
- Check that you can access your HMRC account and identify missing information before the deadline approaches.
Not every expense or payment qualifies for tax relief. If you are unsure how something should be treated, ask before submitting. Our Self Assessment service can help you prepare and review your return, while our sole trader accounting support can help keep business records organised.
Budget for the full January payment
Your January bill may include both the balance for 2025/26 and a first payment on account towards the following tax year. Where payments on account apply, a second instalment is usually due on 31 July. Check your HMRC statement rather than assuming the amount due is only the tax remaining for last year.
Review HMRC’s payment guidance and allow enough time for your chosen payment method. Filing a return and paying the bill are separate steps.
Take the next step
Start with your records, confirm what you owe and make a plan for payment. For support tailored to your circumstances, book an introductory call with Griffith Accountants.
Checked against HMRC guidance on 24 October 2026. This article provides general information; the treatment and deadlines that apply depend on your circumstances.
