Company Accounts Deadlines: Start From Your Year-End Date

Every filing deadline a limited company has flows from one single date: your year end. Once you know that date you can work out when your accounts are due at Companies House, when Corporation Tax has to be paid, when the company tax return has to be filed, and when your confirmation statement is due.

The confusing part is that these four things are not due at the same time, and they are not all owed to the same organisation. This guide shows you how to map the whole year from your year-end date, so nothing arrives as a surprise.

Key takeaways

• Your accounting reference date is your official year end, and almost every other deadline is calculated from it.
• Annual accounts are normally due at Companies House nine months after your year end.
• Corporation Tax is normally payable nine months and one day after your year end, but the return is not due until twelve months after it.
• The confirmation statement runs on its own clock, based on incorporation rather than your year end.
• Your first year is the exception: first accounts are usually due 21 months after incorporation.

What is an accounting reference date?

Your accounting reference date, or ARD, is the date Companies House holds as the end of your financial year. When you incorporate a company it is set automatically to the last day of the month in which the company was formed. A company incorporated on 14 March 2026 therefore gets an ARD of 31 March, and its first financial year runs to 31 March 2027.

You can look your own date up for free on the Companies House register. It takes about thirty seconds, and it is worth doing rather than relying on memory, because a previous accountant may have changed it at some point.

Deadline one: annual accounts at Companies House

For most private limited companies, annual accounts must reach Companies House nine months after the end of the accounting period. A 31 March 2027 year end means accounts are due by 31 December 2027. A 30 September 2026 year end means they are due by 30 June 2027.

These are the statutory accounts: a balance sheet, a profit and loss account and supporting notes, prepared to a recognised standard. Small companies can usually file a reduced version at Companies House. What a small company may file is set out on GOV.UK's guidance on annual accounts.

Late filing triggers an automatic penalty from Companies House. It increases in bands the longer the accounts are outstanding, and it can be doubled if you also filed late in the previous year. Unlike some tax penalties it is charged even if the company owes no tax and made no profit at all. Check the current amounts on GOV.UK before assuming a short delay is cheap.

Deadline two: paying Corporation Tax

This is the one directors most often get wrong, because the payment falls due before the return does. For a company that is not large enough to pay by quarterly instalments, Corporation Tax is normally due nine months and one day after the end of the accounting period.

So for that same 31 March 2027 year end, the tax is payable by 1 January 2028. You have to know roughly what you owe before the accounts are formally filed, which is the practical reason to prepare accounts early rather than at the deadline. HMRC charges interest on tax paid late. The current rules are on GOV.UK's pay Corporation Tax page.

Deadline three: filing the company tax return

The company tax return, the CT600, goes to HMRC and is normally due twelve months after the end of the accounting period. For a 31 March 2027 year end the return is due by 31 March 2028 — three months after the tax itself was payable.

In practice almost nobody works to that date. Since you need the accounts to work out the tax, and the tax is due at nine months and a day, most companies prepare the accounts and the tax return together and file them both well before the Companies House deadline.

Deadline four: the confirmation statement

The confirmation statement is not an accounts deadline at all, which is exactly why it gets missed. It confirms that the details Companies House holds — registered office, directors, shareholders, people with significant control, SIC codes — are still correct.

It runs on a review period that usually starts from the date of incorporation rather than from your year end, and the statement must be filed within 14 days of the end of that review period. So a company incorporated in March will often have an accounts deadline in December and a confirmation statement due the following March.

The four deadlines side by side

Your first year works differently

A brand new company does not get nine months. First accounts are normally due 21 months after the date of incorporation, which sounds generous but covers a longer first period. A company incorporated on 14 March 2026 with an ARD of 31 March 2027 has a first accounting period of just over twelve months, and first accounts due in December 2027.

There is a further wrinkle. Because a first accounting period can run longer than twelve months, HMRC may split it into two periods for Corporation Tax: one of twelve months and a short one covering the remainder. That can mean two tax returns for your first year. GOV.UK explains this on its first company accounts and return page.

Step by step: map your own year

1. Look your company up on the Companies House register and note the accounting reference date.
2. Add nine months to that date. That is your accounts filing deadline.
3. Add nine months and one day. That is when Corporation Tax is payable.
4. Add twelve months. That is the latest date for the CT600.
5. Note the confirmation statement date shown on the register, and diarise it separately.
6. Work backwards: set a reminder three months before the accounts deadline to have the bookkeeping finished.
7. Redo the whole list after any change of year end, because every date moves with it.

Worked example (illustrative example)

"Northbridge Interiors Ltd", an invented illustrative example, was incorporated on 12 September 2025, so Companies House set its accounting reference date to 30 September. Its first accounting period runs to 30 September 2026.

That gives the company four separate dates to track. Corporation Tax on the first period is payable by 1 July 2027. The first accounts are due at Companies House 21 months after incorporation, in June 2027. The first company tax return is due by 30 September 2027. And the confirmation statement runs from the September incorporation date, unconnected to any of those.

The director assumed that "accounts by June" meant nothing was needed until the spring. In fact the bookkeeping had to be complete by around March 2027 for the tax figure to be known in good time and for the money to be set aside. Working backwards from the earliest date, rather than forwards from the latest, is the whole trick.

Common mistakes

• Assuming the tax deadline is the filing deadline. Payment is due at nine months and a day; the return is not due for another three months.
• Treating the confirmation statement as part of the accounts. It is a separate filing running on a separate clock.
• Leaving the bookkeeping until the deadline month. You cannot calculate tax from incomplete records, and rushed records cost more to fix.
• Changing the year end without checking the knock-on effect. Shortening a period can bring a filing deadline forward sharply.
• Thinking a dormant or loss-making company is exempt. Filing obligations and late filing penalties apply regardless of profit.

Getting it handled

If you would rather have the dates tracked for you, our company accounts service and corporation tax service cover preparation and filing on fixed fees, and company accounts start from £350 per year. If you are still deciding what level of support you need, our guide to what is actually included in limited company packages is a good place to start. Good records make all of this cheaper, so see also bookkeeping vs doing it yourself.

Not sure which of your dates comes next? Get in touch and we will map your filing year for you.