Home / Self Assessment deadlines for sole traders
Sole traders must file a Self Assessment return each year and pay any tax due by the relevant deadlines. The filing deadline and the payment deadline are not the same thing — missing either carries a cost. Using this calculator throughout the year rather than only in January gives you time to build the reserve before the demand arrives.
5 October: register as self-employed with HMRC by this date if you became self-employed in the prior tax year and have not yet registered. Failure to register on time can result in penalties.
31 October: paper Self Assessment returns for the previous tax year must be filed by this date. Most sole traders file online and are not affected by the earlier paper deadline.
31 January: online Self Assessment returns for the previous tax year (ending 5 April) must be filed by this date. Any tax still outstanding for the prior year is also due on 31 January, along with the first payment on account for the current tax year.
31 July: second payment on account for the current tax year. This date has no associated filing requirement — it is a payment-only deadline.
You must file a return if you are self-employed as a sole trader and your gross trading income (before expenses) exceeded £1,000 in the tax year. This covers freelancers, contractors, tradespeople, consultants and anyone else earning from self-employment.
Other common reasons to file include: total income exceeding £100,000; untaxed income from property rental above the £1,000 property allowance; income from abroad; or HMRC specifically issuing you a notice to file. If HMRC sends you a notice, you must file even if you have nothing to declare.
If you stop being self-employed and have no other reason to file, you need to tell HMRC so they cancel your future filing obligation. Not filing when required will result in automatic penalties; continuing to receive filing notices while not submitting compounds the problem.
A £100 automatic penalty applies for a return filed even one day late, regardless of whether any tax is owed. After three months, an additional penalty of £10 per day applies (up to a maximum of £900). After six months, a further 5% surcharge (or £300, whichever is greater) is added. After twelve months, another 5% surcharge applies.
Late payment attracts interest from the day after the due date. After 30 days, a 5% late payment surcharge applies to the unpaid amount, with further 5% surcharges at six and twelve months.
If you are going to file late, do so as soon as possible — the penalties grow significantly with time. If you cannot pay the full amount, contacting HMRC before the deadline to arrange a Time to Pay agreement is considerably better than waiting.
A tax estimate has most value when it is used well before the payment date. Running the calculator in April or May — at the start of the new tax year — gives you twelve months to build the reserve. Running it again at mid-year lets you adjust if income has changed.
The monthly set-aside figure tells you what to move into a separate account each month. If you have been consistent with this throughout the year, January should not require emergency action.
The calculator also helps you assess whether your bill will exceed the £1,000 threshold for payments on account. If it does, the January demand includes both the prior year's balance and a payment on account for the current year — typically making it around 150% of the annual bill rather than the bill itself.
The homepage calculator is the fastest way to turn this guidance into a concrete monthly take-home and tax reserve estimate.
Online returns for the tax year ending 5 April must be filed by 31 January the following year. Paper returns have an earlier deadline of 31 October.
An automatic £100 penalty applies from day one of being late, even if no tax is owed. Penalties increase significantly after three, six and twelve months of continued late filing.
HMRC offers Time to Pay arrangements for those who cannot pay in full by the deadline. Apply before the deadline rather than after — interest still applies but it avoids late payment surcharges in some cases.
Yes, if HMRC has issued you a notice to file. The £100 late filing penalty applies regardless of whether any tax is owed.