Key UK tax and Companies House deadlines for small businesses

Missing a deadline is the most expensive mistake a small business can make that has nothing to do with how well the business is doing. Penalties and interest arrive automatically, and they arrive whether or not you owed any tax. Here are the standard dates to keep in the diary. Yours may differ depending on your year end, so if you are not sure, ask us.

Self Assessment (sole traders, partners, landlords and company directors with untaxed income)

• 5 October — tell HMRC you need to complete a return for the previous tax year if you have not filed one before.
• 31 October — paper returns must reach HMRC by 11:59pm.
• 31 January — online returns must be submitted by 11:59pm, and any tax you owe must be paid by the same time.
• 31 July — second payment on account, if you make payments towards next year's bill.

The tax year runs from 6 April to 5 April.

Limited companies

• Corporation Tax payment — usually due 9 months and one day after the end of your accounting period.
• Company Tax Return (CT600) — due 12 months after the end of the accounting period it covers. Note that the payment falls due before the return.
• Annual accounts at Companies House — 9 months after your company's financial year ends (21 months after incorporation for the very first set).
• Confirmation statement — at least once every 12 months, filed within 14 days of the end of your review period.

VAT

If you are VAT registered, your return and payment are usually due one calendar month and 7 days after the end of each VAT period, and the payment must have reached HMRC by then even if the date falls on a weekend or bank holiday.

Making Tax Digital for Income Tax

From 6 April 2026, sole traders and landlords with qualifying income over £50,000 must keep digital records and send quarterly updates to HMRC through compatible software, with the threshold falling to £30,000 from April 2027 and £20,000 from April 2028. We cover what that means for you in our Making Tax Digital guide.

How we help

Every client of SME Outsourcing has their deadlines tracked for them. We prepare and file accounts, returns and confirmation statements ahead of time, tell you what to pay and when, and deal with HMRC and Companies House on your behalf. If you have already missed a date, call us — the sooner it is sorted, the smaller the penalty.

Sources: GOV.UK — Self Assessment deadlines · GOV.UK — Company Tax Returns · GOV.UK — Annual accounts · GOV.UK — Confirmation statement · GOV.UK — VAT Returns · GOV.UK — Making Tax Digital for Income Tax