Self Assessment 2025/26: Deadlines and Records
The 2025/26 tax year ran from 6 April 2025 to 5 April 2026. If you need to complete a Self Assessment return, preparing it early provides more time to check the figures and budget for the tax due.
Who May Need to File?
A return may be required where you received:
- Self-employment income above the trading allowance
- Rental income
- Untaxed savings, dividends or investment income
- Foreign income or taxable capital gains
- Income requiring a tax charge or repayment claim
Other circumstances can also create a filing requirement. Do not assume that being taxed through PAYE means a return is never needed.
Key Deadlines
For the 2025/26 return, the main dates are:
- 5 October 2026: normally register for Self Assessment if newly required
- 31 October 2026: paper return deadline
- 31 January 2027: online return and payment deadline
- 31 July 2027: second payment on account, where applicable
Late filing can trigger an automatic penalty even where no tax is due. Interest and further penalties can apply to late payments.
Information to Gather
Depending on your circumstances, collect:
- P60s, P45s and benefits information
- Pension statements
- Self-employment income and expense records
- Property income and costs
- Bank interest and dividend statements
- CIS deduction statements
- Capital gains information
- Pension contributions and Gift Aid donations
- Details of tax already paid
If documents are missing, request replacements early. Do not guess figures without considering whether a provisional return and later amendment are appropriate.
Understanding the January Payment
The amount due on 31 January 2027 may include a balancing payment for 2025/26 and the first payment on account for 2026/27. This is why a first tax bill can be larger than expected.
Completing the return early does not mean paying early. It gives you advance notice of the liability.
Keep evidence for every material figure and retain the submitted return and final tax calculation.
If profits or income fell during 2025/26, it may be possible to reduce payments on account. The claim should be reasonable: reducing them too far can result in interest when the final liability is calculated. Any earlier payments and PAYE deductions should also be checked against HMRC’s records.
GMS Accountants prepares Self Assessment returns for individuals, landlords and sole traders in Cambridge and Nottingham. Contact us before the January rush.
