Register for Self Assessment by 5 October 2026, and what happens if you miss it

Published 20 September 2026.

If you started freelancing during the 2025/26 tax year, 5 October 2026 is the date that matters. It is the deadline to tell HMRC you need to file a Self Assessment tax return, and it falls two weeks from now.

It is also the deadline most new freelancers have never heard of, because it sits nearly four months before the 31 January one everybody knows about.

What the 5 October deadline actually is

It is not a filing deadline and it is not a payment deadline. It is a notification deadline: you are telling HMRC that a return will be coming.

You must tell HMRC by 5 October 2026 if, for the tax year that ran from 6 April 2025 to 5 April 2026, you need to complete a return and you have either:

• never sent a tax return before, or
• registered before but did not need to send a return for the 2024-25 tax year

You do that by registering for Self Assessment on GOV.UK.

Do you actually need to file?

The threshold that catches most new freelancers is this one: you must send a return if you were self-employed as a sole trader and earned more than £1,000 in the tax year, before taking off anything you can claim tax relief on.

Read that last part twice. The £1,000 is measured on what you invoiced, not what you kept. Expenses, equipment and the rest come off afterwards. A freelancer who billed £4,000 and spent £3,500 on kit is inside the rules, however small the profit looks.

You may also need to file for reasons that have nothing to do with self-employment, including untaxed income from renting out property, savings interest, dividends, tips and commission, or foreign income. Capital Gains Tax and the High Income Child Benefit Charge both pull people in as well.

If you are not certain, GOV.UK has a checker tool, and it does not send your answers to HMRC.

What really happens if you miss it

This is where most coverage goes wrong, in both directions. Missing 5 October is neither harmless nor an automatic fine.

Your filing deadline moves, and that part is in your favour. If you register after 5 October, HMRC writes to you with a different deadline to send the return by, and that deadline is three months from the date on the letter or email. Register in November and you are not scrambling for 31 January.

Your payment deadline does not move. You still have to pay what you owe by 11:59pm on 31 January 2027. Extra filing time is not extra paying time, and that trips people up badly, because working out what you owe is the hard part.

The penalty is conditional, not automatic. A "failure to notify" penalty applies if you register after 5 October and do not pay all of your tax bill by 31 January. It is calculated on the amount still left to pay, and it can arrive up to twelve months after HMRC receives your return. Clear the bill in full by 31 January and there is nothing for that penalty to bite on.

So the honest summary is that missing 5 October is recoverable, and registering late while paying on time often costs nothing. What you must not do is miss it and then miss January too.

One practical catch: registering gets you a Unique Taxpayer Reference, and you cannot file without it. It does not arrive instantly. Leaving registration until January means waiting on a UTR while the payment clock runs.

The deadlines that follow

Date	What is due
5 October 2026	Tell HMRC you need to file for 2025/26
31 October 2026	Paper tax return for 2025/26
30 December 2026	Online return, if you want the tax collected through your tax code
31 January 2027	Online tax return, plus payment of what you owe
31 July 2027	Second payment on account, if you make them

The 30 December date is worth a look if you are also employed. File by then and you can ask for the tax to be collected through your PAYE code across the following year rather than paying it in one go.

If you file or pay late anyway

Late filing carries an initial £100 penalty even if you owe no tax at all. After three months it becomes £10 a day up to a maximum of £900. At six months there is a further 5% of the tax due or £300, whichever is greater, and the same again at twelve months.

Late payment is charged separately: 5% of the unpaid tax at 30 days, six months and twelve months, plus interest at 7.75%, the rate in force since 9 January 2026 and set at the Bank of England base rate plus 4%.

The two run in parallel. Filing on time while paying late still costs you, and paying on time while filing late costs you the £100 regardless.

If Making Tax Digital also applies to you

Registering for Self Assessment is separate from Making Tax Digital, and being inside one does not settle the other. MTD for Income Tax went live on 6 April 2026 for sole traders and landlords with qualifying income above £50,000, and it runs on quarterly updates rather than a single annual return.

If that is you, the next quarterly update is due on 7 November 2026. We covered why the 7 November update also clears a missed 7 August, and the summer deadlines that preceded it.

The two systems overlap for now. Quarterly updates are summaries, not filings, so your 2025/26 Self Assessment return is still due by 31 January 2027 whichever applies to you.

What to do now

1. Work out whether you crossed £1,000 in turnover between 6 April 2025 and 5 April 2026. Turnover, not profit.
2. Register before 5 October if you did, or if any of the other reasons apply. It takes minutes, and the UTR takes longer.
3. If you have already missed it by the time you read this, register anyway, then focus everything on paying in full by 31 January. That is the thing that decides whether a penalty lands.
4. Start setting money aside now rather than in January. Our guide to managing your freelance finances and taxes covers what to put by and what you can claim.
5. If you are still getting set up, the freelance startup checklist covers the rest of the paperwork.

This is general information, not tax advice. Figures and deadlines are correct as at 20 September 2026. Check GOV.UK or speak to an accountant about your own position.

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