31-Jan-26: Self-Assessment Deadlines

31st January 2026 Self-Assessment electronic filing & payment deadline

The forthcoming Self-Assessment payment & electronic filing deadline of 31^st January 2026 is just a few weeks away, in respect of 2024/25 tax returns. This deadline applies to the:

• Electronic submission of an individual’s, partnership’s, estate’s and/or Trust’s 2024/25 Self-Assessment tax return to HMRC,
• Payment of 2024/25 (balancing) tax liability for some taxpayers,
• Payment on account (1st) of 2025/26 tax liability for some taxpayers.

SA303 ‘reduction in payments on account’ elections/claims

Where appropriate, it is possible to reduce 2025/26 payments on account before 31^st January 2026, by making the required claim online, where self-assessment income tax liabilities are expected to be lower in the current 2025/26 tax year, compared to the 2024/25 tax year, on which automatically generated 2025/26 payments on account are based.  However, care should be taken when looking to make a claim because late payment interest (and possibly penalties) can be charged where it transpires payments on account reductions have been excessively made.

Penalties & Interest Charges

HMRC’s late payment interest is set to be reduced from 8% to 7.75% from 9^th January 2026. Interest charges will apply to both the balancing tax liability relating to the 2024/25 tax year as well as the first payment on account towards the 2025/26 tax year (where relevant).

For self-assessment tax returns that are not electronically filed by the 31^st January 2026, a late filing penalty of £100 will be charged immediately.

For 2024/25 self-assessment tax liabilities paid late, a 5% charge will be applied at the following intervals:

1. 30 days late
2. 6 months late
3. 12 months late

The 5% charge will be applied to the outstanding tax liabilities relating to the 2024/25 tax year on these dates.

Can’t Pay Your Bill In Full?

If you cannot pay your self-assessment tax bill in full, we recommend that you look to contact HMRC as soon as possible.

Additionally, you may be able to set up a payment plan to pay any tax liabilities dues by way of instalments. This is called a ‘Time to Pay’ arrangement. This can also be set up online subject to the amount you owe.

The link to HMRC setting up a payment plan is below:

https://www.gov.uk/difficulties-paying-hmrc/pay-in-instalments

Get In Touch

For more information or advice on Self-Assessment and the 31^st January 2026 self-assessment tax return electronic filing and payment deadline, please contact your Whitings representative or your local Whitings office.