Upcoming Self-Assessment Deadlines

Taxpayers who complete a self-assessment tax return should be aware of several important HMRC self-assessment deadlines.

Missing these self-assessment deadlines may result in penalties and interest and as we are approaching the end of the year, it’s a good time to highlight these.

Paper filing deadline

For individuals who submit a paper self-assessment tax return, HMRC requires the return to be received by 31 October following the end of the relevant tax year.

For the 2025/26 tax year, paper returns must reach HMRC by 31 October 2026.

Paper filing is available, however, most taxpayers submit their returns electronically.

Electronic filing deadline

Taxpayers submitting their self-assessment tax return electronically must ensure this is submitted by 31 January following the end of the relevant tax year.

For the 2025/26 tax year, the online filing deadline is 31 January 2027.

Registering for Self-Assessment

If you need to file a self-assessment tax return for the first time, you must notify HMRC by 5 October after the end of the tax year in which you received untaxed income.

Important Self-Assessment deadlines:

31 January – Tax payment due

31 January – First payment on account due (if applicable)

31 July – Second payment on account due (if applicable)

Payments on account are due if your self-assessment liability was £1,000 or over for the previous tax year. HMRC usually split this in to two equal payments. If you earn more than estimated in the payments on account, you may still have tax to pay on top. This is a ‘balancing payment’. If you earn less than estimated, you may be able to claim a refund.

What happens if you miss a deadline?

Missing a self-assessment deadline can trigger automatic penalties and interest.

Should you require assistance, please do not hesitate to contact your local Perrys branch.