Deadline for Paying Tax Underpayments Through PAYE – 30 December

Deadline for paying tax underpayments

As we approach the end of the year, now is the perfect time to make sure your tax affairs are in order. Read on if you’ve had a Self-Assessment underpayment for the 2024/25 tax year. One key date that often catches taxpayers out is 30 December. This deadline is to submit your tax return if HMRC are to collect certain underpayments through your PAYE tax code.

Tax underpayments through PAYE

If you owe less than £3,000 and you’re paid through PAYE, HMRC can allow the underpayment to be collected automatically. This may be from your salary or pension during the following tax year. This can be a helpful way to spread the cost, avoiding the need to make a lump-sum payment by 31 January.

This option is only available if your online Self-Assessment return is filed by 30 December 2025. It also only available if your 2025/26 PAYE income is high enough for the adjustment to be made. Miss the deadline, and you’ll need to settle any amount owed in full by 31 January 2026.

When is the deadline?

With just weeks left before the deadline, now is a good time to gather your documents, check for any untaxed income, and ensure your return is complete and accurate. Submitting early also gives you time to correct any errors and avoid delays caused by the January rush.

If you’re unsure whether your underpayment qualifies for PAYE collection, or if you’d like support completing your tax return, our team is here to help.

For more information or to see how Perrys Accountants can help you, please contact your local branch.