When your UK limited company filings are actually due

A UK limited company has three recurring obligations, and they do not share a deadline. Each is measured from your accounting reference date, which is the last day of your financial year.

Annual accounts to Companies House: 9 months after the period end Corporation tax PAYMENT to HMRC: 9 months and 1 day after the period end Company tax return (CT600) to HMRC: 12 months after the period end

The ordering catches people out every year. Corporation tax is payable three months before the return that calculates it is due. You are expected to work out what you owe, pay it, and file the paperwork afterwards. Waiting for your accountant to finish the return before paying is a late payment, and interest runs from the due date.

A confirmation statement is separate again. It is due at least once every 12 months, within 14 days of the end of your review period, and it confirms your registered details rather than reporting any numbers.

A company's first accounts run from incorporation, not from the start of a tax year, and are due 21 months after the date of incorporation.

Three cases that normally need an accountant are worked out here rather than assumed away:

• A first period longer than 12 months. A corporation tax period cannot exceed 12 months, so a long first period is split in two. You get two payment dates and a single CT600 deadline, which is what HMRC expects.
• A changed year end. Nothing to tell us. Every date is measured from the accounting reference date on the register today, so a shortened or extended year is already in the answer.
• A newly incorporated company. The first period is dated from incorporation. If Companies House has not published your accounting date yet, the corporation tax dates are left out rather than guessed.

Take a company with a 31 March 2027 year end.

• 1 January 2028 - corporation tax is due. Nine months and one day after 31 March 2027.
• 31 December 2027 - annual accounts are due at Companies House. Nine months after the period end, so this one actually falls a day before the tax payment.
• 31 March 2028 - the CT600 is due at HMRC. Twelve months after the period end.

So the sequence a founder experiences is: file accounts, pay tax the next day, then file the tax return three months later. If you plan cash around the CT600 deadline you will be three months late paying, and HMRC charges interest from 1 January regardless of when the return arrives.

Companies House and HMRC run entirely separate penalty regimes. Missing both deadlines means two penalty tracks running at once, and neither reduces the other.

Companies House penalties double if you file late two years running. Late filing also puts a public marker on your company record, which shows up in supplier and lender credit checks.

Source: GOV.UK: accounts and tax returns for private limited companies, checked 2026-08-08.

The dates above are the ordinary case. These three situations move them:

• Profits above £1.5m. Corporation tax is then paid in quarterly instalments starting during the accounting period, not nine months after it. Above £20m the instalments start earlier still. The payment dates here assume you are below that.
• Trading that started after incorporation. Your first corporation tax period is dated from incorporation, because the register does not publish the date a company starts trading. If you began trading later, the tax dates move back and you have slightly longer than shown. The rows say so where it applies.
• Dormant is not the same as inactive. A dormant company files simpler accounts and no CT600. Getting the classification wrong creates a filing you did not know you owed.