Missing a tax deadline costs money - HMRC and Companies House impose automatic penalties that escalate quickly. This guide covers every recurring deadline for UK small businesses: limited companies and sole traders.
Self assessment (sole traders and directors)
The self assessment tax year runs 6 April to 5 April. Key dates:
- 5 April: tax year end
- 31 July: second payment on account due (for the previous tax year)
- 5 October: register for self assessment by this date if you were newly self-employed in the year to 5 April
- 31 October: paper self assessment filing deadline (if filing on paper - almost no one does this)
- 31 January: online self assessment filing deadline AND payment of any tax owed AND first payment on account for the current year
Late filing penalty: automatic £100 even if no tax is owed. Additional daily penalties (£10/day) from 3 months late. Further penalties at 6 and 12 months late.
Corporation tax (limited companies)
Corporation tax deadlines are set relative to your company's accounting period end date - not the calendar year.
- 9 months and 1 day after period end: corporation tax payment due
- 12 months after period end: CT600 (corporation tax return) filing deadline
Example: company year end 31 March 2025 → tax payment due 1 January 2026 → CT600 due 31 March 2026.
Late payment interest: HMRC charges interest on unpaid corporation tax at the Bank of England base rate + 2.5%. Late filing penalty: £100 immediately, £200 if more than 3 months late, plus tax-geared penalties for persistent late filing.
Companies House (limited companies)
- Annual accounts: 9 months after accounting period end for private companies (6 months for PLCs)
- Confirmation statement: within 14 days of the anniversary of incorporation (or the date of your last confirmation statement)
- Changes to company details: certain changes (registered address, directors, share capital) must be notified to Companies House promptly - usually within 14 days
Late accounts penalty: £150 for up to 1 month late, £375 for 1–3 months, £750 for 3–6 months, £1,500 beyond 6 months. Penalties double if you file late two consecutive years.
VAT (VAT-registered businesses)
VAT returns cover a quarterly accounting period. The deadline is 1 month and 7 days after the end of each VAT period. Most businesses are on a standard quarterly cycle (periods ending March, June, September, December).
- VAT period ending 31 March → return and payment due 7 May
- VAT period ending 30 June → return and payment due 7 August
- VAT period ending 30 September → return and payment due 7 November
- VAT period ending 31 December → return and payment due 7 February
All returns must be submitted via Making Tax Digital (MTD) compatible software. Late filing: HMRC's penalty points system - 4 penalty points triggers a £200 fine, then £200 per subsequent late return.
PAYE and payroll (employers)
- On or before each payday: Full Payment Submission (FPS) to HMRC via RTI
- 19th of each month: PAYE and NI payment due to HMRC (22nd if paying electronically)
- 5 April: tax year end - produce P60s for all employees
- 6 July: P11D filing deadline (reporting benefits in kind) and P11D(b) for Class 1A NI
- 19 July: Class 1A NI payment due on benefits in kind
- 31 May: P60s must be given to employees by this date
CIS (Construction Industry Scheme)
- 19th of each month: CIS monthly return due to HMRC (22nd if paying electronically)
- Same date: CIS deductions payment due to HMRC
- 19 April: CIS return and payment for the year end (March)
A note on how we manage deadlines
We track every deadline for every client and send reminders well in advance. You shouldn't need to memorise these dates - but it's useful to understand what's coming up. If you're taking on a new accountant, deadlines falling in the next 2–3 months should be one of the first things you discuss.
Book a free call → and we'll confirm which deadlines apply to your business right now.