Missed deadlines are the most avoidable cost in self-employment — automatic penalties for being late with something you could have done any time. Here's every date, in order, so nothing sneaks up on you.
The UK tax year runs 6 April to 5 April. Almost every self-employed deadline is pinned to it. The ones that carry automatic penalties — meaning you're fined even if you owe nothing or are only a day late — are the ones to lock in: the 5 October registration deadline, the 31 January filing-and-payment deadline, and (increasingly) the Making Tax Digital quarterly dates. The full calendar below lays them all out in order.
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The quarterly MTD dates only apply if your gross self-employment plus property income is over the threshold — £50,000 now, £30,000 from April 2027, £20,000 from April 2028. Full detail in our MTD guide. If you're not in scope yet, ignore the quarterly rows above and focus on 5 October, 31 January and 31 July.
Honestly? Hand the calendar to someone whose job is to watch it. Every one of our packages includes us tracking every deadline that applies to you, chasing you before HMRC ever could, and filing on time — so the only date you need to remember is the one where you decided to stop worrying about dates. Get started.
5 October to register for Self Assessment, 31 January to file your online return and pay (plus the first payment on account), and 31 July for the second payment on account. If you're in Making Tax Digital, add quarterly updates on 7 August, 7 November, 7 February and 7 May.
An automatic £100 penalty for a late return even if you owe no tax, then £10 per day after three months up to £900, with further penalties at 6 and 12 months. Late payment adds interest and 5% surcharges.
The second payment on account — an advance instalment towards your next tax bill. No return or reminder comes with it, which is why it's the most commonly missed self-employed deadline.
Only if you file on paper — which few people do. Filing online extends your deadline to 31 January, so almost everyone should ignore the 31 October paper deadline.
