Corporation Tax deadlines summary

The four annual obligations

Limited companies have four recurring deadlines you should diary as soon as your accounting period is set:

• Annual accounts at Companies House: 9 months after period end (21 months from incorporation for first set)
• Corporation Tax payment: 9 months and 1 day after period end
• CT600 at HMRC: 12 months after period end
• Confirmation statement at Companies House: annually with a 14-day filing window

Worked example

Company year ends 31 March 2025:

• 1 January 2026: Corporation Tax payment due
• 31 December 2025: annual accounts due at Companies House
• 31 March 2026: CT600 due at HMRC
• Confirmation statement: within 14 days of your statement date (separate from year end)

Why payment is due before the return

The 9-months-and-1-day payment deadline is three months earlier than the 12-month CT600 filing deadline. In practice this means most companies file the CT600 (and accounts) before the payment deadline so they know what they owe.

Penalties for missing each

• Late accounts at Companies House: £150 → £375 → £750 → £1,500 (private company; doubled if late two years running)
• Late CT600 at HMRC: £100 → £200 → 10% of unpaid tax → another 10%
• Late Corporation Tax payment: daily interest from day one
• Late confirmation statement: can lead to strike-off action