ToolsCorporation Tax deadline calculator
Corporation Tax deadline calculator
Enter your accounting period end date to see exactly when your CT600, Corporation Tax payment and Companies House accounts are due.
Usually your accounting reference date (ARD) — the last day of your company's financial year.
These dates assume a standard 12-month accounting period. Your first accounts, a period you have shortened or extended, or a period longer than 12 months can have different deadlines — a long first period is even split into two returns for Corporation Tax. Always confirm the exact dates on your Companies House record and in your HMRC account. General guidance, not tax advice.
Common questions
When is my CT600 due?
Your Company Tax Return (CT600) is due 12 months after the end of your accounting period. This is later than the Corporation Tax payment deadline, which catches people out.
When do I have to pay Corporation Tax?
For most small companies, Corporation Tax is due 9 months and 1 day after the end of your accounting period — before the CT600 filing deadline.
When are my accounts due at Companies House?
Annual accounts are normally due 9 months after your accounting period ends. First accounts for a newly incorporated company are due 21 months after the date of incorporation.
What if my accounting period is not 12 months?
Shortened, extended or first accounting periods change these dates, and a period longer than 12 months is split into two returns for Corporation Tax. Always confirm against your Companies House record and HMRC account.