Key Takeaways
- The UK tax year for 2025/26 runs from 6 April 2025 to 5 April 2026, and HMRC uses this period to assess your income, expenses, and tax return.
- Most UK tax deadlines follow the same annual pattern.
- Sole traders must register for Self Assessment and submit a tax return if required.
- Limited companies have separate Corporation Tax payment and filing deadlines, based on their accounting year rather than the tax year.
- VAT-registered businesses must submit VAT returns regularly, on a quarterly basis.
- Employers must meet monthly PAYE and National Insurance deadlines.
- Missing a deadline can lead to automatic penalties, daily fines, and interest, even if no tax is owed.
Some dates will change a little from year to year but the UK tax deadlines always broadly fall at the same time, so its good practice to remember when they are.
Table of contents
1. Key UK tax year and tax return deadlines for 2025/2026
| Category | Tax Year / Period | Deadline | What It Means |
|---|---|---|---|
| Tax Year Start | 2025/26 | 6 Apr 2025 | Tax year begins (income and gains count from this date). |
| Tax Year End | 2025/26 | 5 Apr 2026 | Tax year finishes. Last day income is counted. |
| Register for Self Assessment | 2025/26 | 5 Oct 2026 | If you need to file a return for this year and aren’t yet registered. |
| Paper Self Assessment Return | 2025/26 | 31 Oct 2026 | Last date to post a paper return for the 2025/26 tax year. |
| Online Self Assessment Return | 2025/26 | 31 Jan 2027 | Most common method. File online by midnight. |
| Tax Payment (“Balancing payment”) | 2025/26 | 31 Jan 2027 | Pay any owed tax for 2025/26 (and first Payment on Account for 2026/27 if due). |
| Second Payment on Account | 2025/26 | 31 Jul 2027 | If your bill is over £1,000 you may need to make this payment. |
| Corporation Tax Paid | Accounting period | 9 months + 1 day after period end | For companies, payment deadline after year-end. (e.g., year ending 31 Mar 2025 → pay by 01 Jan 2026). |
| Corporation Tax Return CT600 | Accounting period | 12 months after period end | File the company tax return with HMRC. |
| VAT Returns | Quarterly | 1 month + 7 days after quarter end | Depends on your VAT periods; e.g., Jan–Mar quarter due 07 May. |
| PAYE / NIC (Employer) | Monthly | 22nd (Electronic) / 19th (Postal) | Monthly payment to HMRC; dates vary by month. |
| P11D Benefits-in-Kind Form | 2025/26 | 6 Jul 2026 | Report employee benefits to HMRC. |
2. UK tax year and return deadlines explained
Tax year start
The UK tax year always begins in early April and marks the point from which income, profits, and gains start being counted for that year.
Tax year end
The tax year finishes the following April, and this cut-off determines which income and expenses belong to that tax year.
Register for Self Assessment
If it’s your first time filing, you must register partway through the following tax year so HMRC knows you need to submit a return.
Paper Self Assessment return
Paper tax returns must be submitted earlier than online ones, usually in the autumn following the end of the tax year.
Online Self Assessment return
Most people file online, with the deadline falling several months after the tax year ends.
Self Assessment tax payment (balancing payment)
Any remaining tax owed for the year must be paid at the same time as the online return deadline.
Second payment on account
If you make payments on account, the second instalment is due halfway through the following tax year.
Corporation Tax payment
Companies must pay Corporation Tax within a fixed period after the end of their accounting year, not the tax year.
Corporation Tax return (CT600)
The company tax return is filed later than the payment deadline, giving time to finalise figures.
VAT returns
VAT returns are submitted regularly, with the deadline shortly after the end of each VAT period.
PAYE and National Insurance
Employer PAYE and NIC are paid monthly, with slightly different deadlines depending on how you pay.
P11D benefits-in-kind forms
Employers must report benefits provided to employees shortly after the tax year ends.
3. What happens if you miss a tax return deadline?
If you miss the Self-Assessment filing deadline, HMRC will charge a fixed £100 penalty. This happens even when you don’t owe any tax.
There’s a room for making things right after it, but…
If you still haven’t filed your return three months later, HMRC adds a £10 daily penalty. This continues up to 90 days, so this could mean an extra £900 in fines.
At the six-month mark, you’ll get an additional penalty of £300, or 5% of the tax you owe. Which penalty you get? It all depends on whichever is higher. The same applies again if you still haven’t filed after 12 months.
If you also miss the payment deadline, HMRC charges interest on the unpaid tax. They may also add late payment penalties – this start at 5% of the amount owed.
Confusing? Let’s check it with an example!
If a freelancer misses the 31 January 2027 filing and payment deadline and doesn’t file until August, they could face the £100 penalty, £900 in daily fines, and two £300 charges!
If they owed £2,000 in tax, they might also pay over £100 in interest and late payment penalties. All of this accounts to more than £1,600 in extra costs.
4. How to appeal a late tax return penalty
What happens if you miss a UK tax deadline?
No need to worry – at first!
If you’ve missed a tax return deadline and received a penalty, you can appeal to HMRC using form SA370. This form allows you to explain why your return was late ask for the penalty to be cancelled.
You might have a reasonable excuse – if that’s the case, HMRC may cancel the penalty. The reasons could be:
- a serious illness
- a bereavement close to the deadline
- problems with HMRC’s online system.
HMRC won’t accept excuses like forgetting the deadline, relying on someone else to file for you, or not understanding the rules.
HMRC can still reject your appeal. If you still think that the penalty is unfair, you can take your case to the First Tier Tribunal, which is an independent body. You’ll need to show clear evidence – such as hospital records, correspondence, or screenshots – to support your claim.
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