Company deadline checker
One date in, three dates out: your accounts, your Corporation Tax payment and your Company Tax Return.
The last day of your company's financial year — for example 31/03/2026. Type it, or use the calendar.
How these dates are worked out
Accounts go to Companies House 9 months after your year end (private companies). Corporation Tax is paid 9 months and 1 day after your period ends — before the return is due. The CT600 itself is filed within 12 months. Your first year works differently — see the CT600 guide.
These dates are worked out only from the period end you type in, so treat them as indicative — a guide, not something to rely on. They don't allow for a changed accounting reference date or a split first-year period, and they can't reflect every exception HMRC or Companies House may apply to your company. Always confirm the exact dates against your Companies House and HMRC records, or with your accountant, before you act on them.
Penalties start the day after the deadline
Late accounts cost £150 within the first month, rising in bands to £1,500. A late CT600 costs £200 as soon as it's late, and £400 past three months. No drama — just file before the dates above. The accounts guide and CT600 guide cover the full penalty tables.