Your online tax return for 2025/26 (the year to 5 April 2026) must reach HMRC by 11:59pm on 31 January 2027. The same day, you must pay any tax still owed for 2025/26 and, for many people, the first payment on account towards 2026/27. A second payment on account follows on 31 July 2027. Filing early does not bring the payment date forward, and it lets you know the bill in good time.
Dates to know
| Date | What happens |
|---|---|
| 5 October 2026 | Deadline to tell HMRC you need to file for 2025/26 (now passed) |
| 31 October 2026 | Paper returns for 2025/26 must reach HMRC |
| 30 December 2026 | File online by this date to have a bill under £3,000 collected through your PAYE tax code |
| 31 January 2027 | Online return for 2025/26; balancing payment for 2025/26; first payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
If you missed the 5 October registration date, register now and still file and pay by 31 January. A failure to notify penalty can be charged, but it is based on tax left unpaid at 31 January, so paying in full by then usually keeps you clear of it. Paper returns must reach HMRC by 31 October 2026; after that date you must file online.
How payments on account work
Payments on account are advance instalments towards the next year's bill. Each one is normally half of last year's Self Assessment liability, covering income tax and, for the self-employed, Class 4 National Insurance. Capital gains tax and student loan repayments are not included, so they are paid in full with the balancing payment.
So on 31 January 2027 you pay the balance for 2025/26 (your total 2025/26 bill less any payments on account you made in January and July 2026), plus half of your 2025/26 liability on account of 2026/27. In someone's first year in Self Assessment, that can mean paying around 150% of the year's bill in one go, which catches many people out.
You do not have to make payments on account if either:
- your Self Assessment liability for the previous year was under £1,000; or
- more than 80% of your total tax for that year was collected at source, for example through PAYE on a salary or pension.
Reducing payments on account
If you expect 2026/27 income to be lower than 2025/26, for example because a business has slowed or a rental property was sold, you can ask HMRC to reduce your payments on account. This is done through your online account, or on form SA303 by post. Claims for 2026/27 can be made up to 31 January 2028.
Be realistic. If your final 2026/27 bill turns out higher than the reduced figure, HMRC charges interest on the shortfall from the original due dates, as if the correct payments on account had been due all along. A claim made negligently or fraudulently can also attract a penalty. Base any reduction on actual figures to date rather than a hopeful guess, which can prove expensive.
Paying through your tax code
If you are employed or receive a UK pension, HMRC can collect a 2025/26 balance of less than £3,000 through your PAYE code over the following tax year (2027/28), instead of asking for a lump sum in January. You must file online by 30 December 2026, and you cannot pay part of a larger bill to bring it under £3,000. Coding out does not cover payments on account.
Penalties and interest if you are late
Late filing penalties for the 2025/26 return are:
- £100 as soon as the return is late, even if no tax is owed;
- after three months, £10 a day for up to 90 days (a maximum of £900);
- after six months, the greater of 5% of the tax due or £300;
- after twelve months, a further 5% or £300, whichever is greater.
Late payment penalties are separate. Under the regime that applies to 2025/26 returns, tax unpaid at 30 days after the due date attracts a 5% penalty, with further 5% penalties at six months and twelve months. On top of this, late payment interest runs daily from the due date, at Bank of England base rate plus 4% (the margin rose from 2.5% in April 2025). The rate moves with base rate, so check the current figure on GOV.UK.
If you have joined Making Tax Digital for Income Tax, a points-based late submission system and a different late payment penalty structure apply from the year you join. Those new rules do not reach back to your 2025/26 return: someone mandated from April 2026 still faces the penalties above for the 31 January 2027 deadline.
If you cannot pay in full, contact HMRC before the deadline. A Time to Pay arrangement lets you clear the debt in monthly instalments, and agreeing one promptly can prevent late payment penalties, although interest still runs. Many people can set one up online once the return has been filed.
Items people often miss
- High Income Child Benefit Charge: if either partner's adjusted net income exceeded £60,000 in 2025/26 and Child Benefit was paid, the higher earner usually owes the charge, which reaches the full benefit at £80,000.
- Rental income: profits from letting, including a room or a property abroad, must be reported unless covered by the £1,000 property allowance.
- Dividends: anything above the £500 dividend allowance is taxable and is often not collected through PAYE.
- Capital gains: disposals of shares, crypto assets or a second property need reporting on the return when your gains exceed the £3,000 annual exempt amount or your total disposal proceeds exceed £50,000, even if a 60-day UK property return was already filed.
- Pension contributions: higher and additional rate taxpayers paying into a personal pension get only basic rate relief automatically. The rest must be claimed on the return: see how to claim higher-rate pension tax relief.
- Gift Aid: the same applies to donations, and they can also reduce adjusted net income for the Child Benefit charge and the personal allowance taper.
Our 2026/27 tax rates card sets out the current allowances and thresholds.
What to do now
- If you have not registered for 2025/26, do it this week, as your Unique Taxpayer Reference can take time to arrive.
- Gather P60s, P11Ds, bank interest, dividend vouchers, rental figures, pension and Gift Aid records, and details of any disposals.
- Aim to file online by 30 December 2026, especially if a small balance could be coded out.
- Check your 31 January figure carefully: balancing payment plus first payment on account.
- If your 2026/27 income will be lower, consider a reasoned claim to reduce payments on account.
- If you will struggle to pay, speak to HMRC about Time to Pay before 31 January.
We prepare returns and handle payments on account for employees, landlords, company owners and investors through our personal tax service. If you would like us to take care of your 2025/26 return, book a consultation.
This article is general information about UK tax, based on the law and HMRC practice at the date shown above. It is not advice, and reading it does not make you our client. Tax rules change and their effect depends on your circumstances, so please speak to us before acting on it.