Last checked October 2026 · by the PaySorted team
The key dates
For the 2025/26 tax year (6 April 2025 to 5 April 2026):
| What | Deadline |
|---|---|
| Register for Self Assessment (if you started in 2025/26) | 5 October 2026 |
| Paper tax return | 31 October 2026 |
| Online return, if you want tax owed collected through your PAYE tax code | 30 December 2026 |
| Online tax return | 31 January 2027 |
| Pay the tax you owe for 2025/26, plus your first payment on account for 2026/27 | 31 January 2027 |
| Second payment on account for 2026/27 | 31 July 2027 |
The same pattern repeats every year: 5 October, 31 October, 31 January, 31 July.
Payments on account
Once your tax bill is over £1,000, HMRC usually asks you to pay towards next year's bill in advance: two payments, each half of last year's bill, due on 31 January and 31 July. You don't make them if less than £1,000 was due, or if more than 80% of your tax was already taken at source.
The first year this happens is a shock, because on 31 January you pay last year's balance plus half of next year's. Put money aside from every job — many trades set aside 20–30% of their profit.
If you know your income is falling, you can ask HMRC to reduce your payments on account. If you reduce them too far, you'll pay interest.
If you work under CIS
The 20% taken off your labour under CIS is an advance payment towards your tax and National Insurance. You claim it back on your Self Assessment return, so many subcontractors are owed a refund. Keep every monthly payment and deduction statement — and file early to get your money back sooner.
Late penalties (2025/26 returns)
| Late filing | Penalty |
|---|---|
| 1 day late | £100 |
| 3 months late | £10 a day, up to £900 |
| 6 months late | 5% of the tax due or £300, whichever is more |
| 12 months late | Another 5% or £300, whichever is more |
Paying late adds 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest at the Bank of England base rate + 4%.
What changes with Making Tax Digital
Making Tax Digital for Income Tax started on 6 April 2026 for sole traders and landlords with qualifying income over £50,000. It extends to over £30,000 from April 2027 and over £20,000 from April 2028. "Qualifying income" is your turnover (before expenses).
If you're in, you send quarterly updates from compatible software:
| Quarter (standard) | Update due |
|---|---|
| 6 April – 5 July | 7 August |
| 6 July – 5 October | 7 November |
| 6 October – 5 January | 7 February |
| 6 January – 5 April | 7 May |
You still file a final return by 31 January, and payment dates don't change. MTD users move to a new points-based penalty system: a £200 penalty once you reach 4 points for missed deadlines, and late-payment penalties of 3% at 15 days and another 3% at 30 days in 2026/27. From April 2027 the new system applies to everyone who files a Self Assessment return.
PaySorted keeps your invoices and expenses digital from day one and syncs them to Xero, QuickBooks, FreeAgent or Sage, so your accountant has what they need for each quarter. See Making Tax Digital for trades.
General information based on gov.uk guidance (checked October 2026), not tax advice. Your accountant can confirm your own deadlines.
Common questions
When is the Self Assessment deadline?
The online return and any tax owed are due by 31 January after the end of the tax year. For 2025/26 that's 31 January 2027. Paper returns are due by 31 October.
What is the penalty for a late tax return?
For 2025/26 returns, £100 straight away, then £10 a day after 3 months (up to £900), then further penalties at 6 and 12 months.
When do I need to register for Self Assessment?
By 5 October after the end of the tax year in which you started self-employment, if your income was over £1,000.
Does Making Tax Digital change the 31 January deadline?
No. You still file a final return and pay by 31 January. MTD adds quarterly updates on top.