Self Assessment 30 December 2026: Pay Through Your Tax Code

Short answer

If you owe less than £3,000 for 2025/26 and already pay tax through PAYE, file your Self Assessment return online by 11:59pm on 30 December 2026 and HMRC can collect the tax through your tax code, over 12 months. If you miss it, you pay another way by 31 January 2027.

Last checked by hand against GOV.UK: 10 October 2026. Sources are linked in each section. HMRC updates its guidance, so always check the source before you act.

Email reminder · planned send date 15 December 2026

The facts

All three must apply: you owe less than £3,000 (a part payment to get under £3,000 doesn't count), you already pay tax through PAYE, and you filed online by 30 December (or on paper by 31 October).
HMRC sets it up automatically if you qualify, unless you ask them not to on your tax return. The tax is taken in equal instalments over 12 months.
It won't work if, for example, you don't have enough PAYE income for HMRC to collect it, or you'd pay more than 50% of your PAYE income in tax.
If you're self-employed, Class 2 National Insurance can't be paid this way unless it's been due since before 6 April 2015.
Everyone else: online return and payment are due by 31 January 2027.

Sources: GOV.UK – Pay your Self Assessment bill through your tax code · GOV.UK – Self Assessment deadlines.

What to do before Christmas

Gather your figures for 2025/26 (6 April 2025 to 5 April 2026).
If you're employed or have a pension and owe a small amount, aim to file online by 30 December.
Got a side hustle? The free side hustle tax checker shows your Self Assessment dates and lets you add them to your calendar.

Questions

Who can pay their Self Assessment bill through their tax code?

GOV.UK says you can if you owe less than £3,000, you already pay tax through PAYE (for example as an employee or with a company pension), and you submitted your online return by 30 December (or paper return by 31 October). You can't make a part payment to get under £3,000.

What happens if I miss the 30 December deadline?

You can't pay through your tax code, so you pay another way. The online return and payment deadline for 2025/26 is still 11:59pm on 31 January 2027.

Is 30 December the Self Assessment deadline for everyone?

No. The online filing and payment deadline is 31 January 2027. 30 December only applies if you want HMRC to collect what you owe through your PAYE tax code.

A short email 1–3 weeks before key UK tax dates: Making Tax Digital quarterly updates, the 31 January Self Assessment deadline and the end of the tax year. Each one says what's due and who it applies to, and links to the GOV.UK source.

How often: about once a month, never more than 2 a month.
What else: occasionally a note about our record-keeping spreadsheets. No spam, and we never share or sell your address.
Leave any time: there's an unsubscribe link in every email.

Not tax or legal advice. This free tool shows dates and figures worked out from the GOV.UK and legislation.gov.uk rules linked on each page, checked on 10 October 2026. Rules change and your situation may differ – always check the source, and speak to an accountant, solicitor or HMRC if unsure. TaxYearSheets is not connected to HMRC or the government.