How the dates are worked out
Confirmation statement
The review period lasts 12 months. The first starts on the day of incorporation; each later one starts the day after the date on the last statement. You then have 14 days to file (GOV.UK). A company incorporated on 18 May 2026 has a first statement date of 17 May 2027, due by 31 May 2027. The confirmation statement guide covers the fee and what to update first.
Accounts
- The first accounts run from incorporation to the accounting reference date, which is the last day of the month in which the first anniversary of incorporation falls (GOV.UK).
- First accounts are due 21 months after incorporation; later accounts are due 9 months after the year end (GOV.UK).
- Months are counted as the Companies Act says: a deadline from a month end lands on a month end, so a 30 June year end gives 31 March, not 30 March (section 443). If a first period is longer than 12 months, the deadline is 21 months from incorporation or 3 months after the period ends, whichever is later (section 442).
Corporation Tax
Tax is paid 9 months and 1 day after the end of each tax period (GOV.UK). A tax period cannot be longer than 12 months, so first accounts that cover more than that need two returns with two payment dates (GOV.UK). Both returns are due 12 months after the end of the accounts period they belong to.
What the calculator cannot know
It works from the rules, not from your company’s record, so it cannot see:
- a confirmation statement filed early (enter its date in the optional fields)
- a changed accounting reference date (enter the period end in the optional fields)
- an extension Companies House has granted
- a company that started trading later than it was incorporated, which changes the tax dates
Your company’s page on the Companies House register shows its actual next dates. Where they differ from these, the register is right.
Philofounder reads those dates from your own Companies House record and reminds you before each one. Try it.