The deadlines at a glance
The 2025/26 tax year ran from 6 April 2025 to 5 April 2026. If you need to report income from that year, these are the dates HMRC works to:
| Deadline | What it is for |
|---|---|
| 5 October 2026 | Register for Self Assessment if you have never filed before or did not need to file for 2024/25 |
| 31 October 2026, 11:59pm | Paper tax return |
| 30 December 2026, 11:59pm | Online return if you want a bill under £3,000 collected through your PAYE tax code |
| 31 January 2027, 11:59pm | Online tax return, payment of the 2025/26 balance, and the first payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
If this is your first return, the registration deadline has just passed. Do not panic: register now, and as long as the return is filed and the tax paid by 31 January 2027 you will not be penalised for the late registration. HMRC gives anyone who registers after 5 October three months from the date it writes to you to file, but the tax itself is still due on 31 January.
Who has to file a 2025/26 return
You need a return if, between 6 April 2025 and 5 April 2026, any of the following applied:
- You had more than £1,000 of gross income from self-employment, including a side hustle, before expenses. The £1,000 is the trading allowance, and it is a test of turnover, not profit, across all your side activities added together.
- You had more than £1,000 of rental income, or more than £2,500 of other untaxed income.
- You or your partner received Child Benefit and one of you had income over £60,000, unless you have moved the High Income Child Benefit Charge to your PAYE code using HMRC's online service.
- You had income over £150,000, were a partner in a business, or had capital gains to report.
- HMRC sent you a notice to file. If you got one but have no income to report, ask HMRC to withdraw it rather than ignore it.
Selling your own unwanted possessions is not trading, so a Vinted clear-out does not count. Buying to resell, making things to sell, delivery work, tutoring and renting a room on Airbnb do. Our side hustle tax guide walks through the line between the two, and the platform guides cover eBay, Vinted, Etsy, Deliveroo, Uber, Airbnb and more.
HMRC already has your platform data
Since January 2024 digital platforms have been required to report sellers to HMRC each January for the previous calendar year. Goods sellers with fewer than 30 sales and under about £1,700 (2,000 euros) in a year are left out; anyone selling services or letting property is reported from the first pound. The report covering January to December 2025 reached HMRC by 31 January 2026, and platforms must give you a copy of what they sent. HMRC's "nudge" letters to sellers who were reported but did not file have been going out since 2025, so if you cross the £1,000 line the safe assumption is that HMRC knows.
Registering and getting a UTR
Register online through GOV.UK. Self-employed people register as a sole trader, which also sets up Class 2 and Class 4 National Insurance; everyone else uses the SA1 route. HMRC posts your 10-digit Unique Taxpayer Reference within about 15 working days, longer in the January rush, and it also appears in the HMRC app and your personal tax account sooner. You then need a Government Gateway account linked to Self Assessment, which can involve a second activation code by post. Registering in October leaves plenty of time; registering on 20 January often does not.
What to gather before you start
- Your income and expenses for the side hustle or business, ideally from a spreadsheet or app kept through the year. Platform annual statements show gross sales and fees.
- P60 or P45 from any employment, and P11D for benefits in kind.
- Bank and building society interest (your bank reports it to HMRC, but you still declare it), dividends and any rental income.
- Child Benefit received if your income is over £60,000.
- Student loan plan type, pension contributions and Gift Aid donations, which can reduce the bill.
- If you are over State Pension age with income above £35,000, your Winter Fuel Payment: the 2025 payment is added to the 2025/26 return as the Winter Fuel Payment charge. Our Winter Fuel Payment guide explains the rule.
Use the side hustle tax calculator to estimate the bill before you file so there are no surprises in January.
Paying the bill: 31 January 2027 and payments on account
The balance for 2025/26 is due on 31 January 2027, the same day as the online filing deadline. If your 2025/26 bill is more than £1,000 and less than 80% of your tax was collected at source, HMRC also asks for payments on account towards 2026/27: half of the 2025/26 bill on 31 January 2027 and the other half on 31 July 2027. Student loan repayments and capital gains tax are left out of the calculation.
Worked example
Priya is employed on £38,000 and made £9,000 profit from tutoring in 2025/26. The side hustle tax calculator shows the profit costs £1,800 of income tax at 20% and no Class 4 National Insurance, because Class 4 is charged only on self-employed profits above £12,570 and her salary does not count towards that limit. Her bill is £1,800. Because it is over £1,000 and none of it was collected at source, on 31 January 2027 she pays the £1,800 plus a first payment on account of £900, which is £2,700 in one go, and another £900 on 31 July 2027. When she files her 2026/27 return the £1,800 already paid on account is deducted from that year's bill.
If you expect 2026/27 profits to be lower you can apply to reduce the payments on account, but if you reduce them too far HMRC charges interest on the shortfall. If this is the first year your bill passes £1,000, budget for the double payment now.
Paying through your tax code
Employees and pensioners who owe less than £3,000 can have it collected through their 2027/28 PAYE code, spread over twelve months without interest, provided the online return is in by 30 December 2026. HMRC refuses if it would take more than half your PAYE income or more than double your usual tax. A part payment to get under £3,000 does not qualify.
Penalties and interest if you miss the deadlines
The late filing penalties apply even if you owe no tax:
| How late | Penalty |
|---|---|
| 1 day | £100 |
| 3 months | £10 a day for up to 90 days (maximum £900) on top of the £100 |
| 6 months | 5% of the tax due or £300, whichever is greater |
| 12 months | Another 5% or £300, whichever is greater |
A return filed a year late with no tax due therefore costs at least £1,600. Late payment is separate: 5% of the unpaid tax at 30 days, another 5% at six months and another at twelve, plus daily interest at the Bank of England base rate plus 4 percentage points, 7.75% from January 2026 while the base rate was 3.75%. You can appeal a penalty if you have a reasonable excuse, such as serious illness or a bereavement, but "I did not know I had to file" is not one.
If you cannot pay
File the return anyway, because filing penalties are the expensive part. Then set up a Time to Pay plan. If you owe £30,000 or less, have filed the return, have no other HMRC payment plans or debts and are within 60 days of the deadline, you can set up monthly instalments over up to twelve months online without speaking to anyone. Interest still runs, but the 5% late payment penalties are not charged while the plan is kept to. Larger or later debts need a phone call to HMRC's payment support line.
Three things that are different this year
- Making Tax Digital has started for some. Sole traders and landlords whose combined gross trading and property income was over £50,000 on their 2024/25 return moved into Making Tax Digital for Income Tax on 6 April 2026. They keep digital records and send quarterly updates (the first was due 7 August 2026, the next on 7 November), but their 2025/26 return is still filed the old way by 31 January 2027. The £30,000 group joins in April 2027 and the £20,000 group in April 2028. Read our Making Tax Digital guide.
- The High Income Child Benefit Charge can be paid through PAYE. Employees whose only reason for filing was the charge can now have it coded out and stop filing. If you have not opted in, you still need a 2025/26 return.
- Pensioners with income over £35,000 see the 2025 Winter Fuel Payment on this return for the first time.
Key figures for the 2025/26 return
These are the rates that apply to the year you are reporting, which differ from the 2026/27 figures on the rest of the site:
- Personal Allowance £12,570; basic rate 20% to £50,270; higher rate 40% to £125,140; additional rate 45%.
- Class 4 National Insurance 6% on profits between £12,570 and £50,270 and 2% above. Class 2 is no longer compulsory, but profits over £6,845 give you a free qualifying year for the State Pension.
- Trading allowance £1,000, property allowance £1,000, dividend allowance £500, Personal Savings Allowance £1,000 for basic-rate taxpayers and £500 for higher-rate taxpayers.
- Dividend tax 8.75%, 33.75% and 39.35% (the 2-point rise to 10.75% and 35.75% applies from 2026/27, not this return).
Our take-home pay calculator and payslip guide help you check the employment figures on your P60 before you copy them across.
Frequently asked questions
When is the Self Assessment deadline for the 2025/26 tax year?
Paper returns by 31 October 2026, online returns and payment by 11:59pm on 31 January 2027.
I missed the 5 October registration deadline. What happens?
Register straight away. There is no penalty as long as you file and pay by 31 January 2027. If HMRC takes a long time to issue your UTR, keep evidence of when you applied.
Do I need to file if my side hustle made less than £1,000?
Not for the side hustle alone, provided your gross receipts from all self-employment combined were £1,000 or less. You may still need to file for another reason.
Can I file early?
Yes. The online return for 2025/26 has been open since 6 April 2026. Filing early does not bring the payment date forward; the tax is still due on 31 January 2027, and you find out the figure months in advance.
What is the £100 penalty for if I owe nothing?
It is a penalty for filing late, not for paying late, so it applies even when the return shows no tax or a refund. If you do not need to file at all, ask HMRC to withdraw the notice before the deadline.