Companies House Accounts Deadline 2026: 9-Month Rule & Penalties

A lot of directors assume there's one big filing deadline a year: get the accounts done, file the tax return, done. In reality your company owes filings to two different bodies on two different clocks, and the one that trips people up most often isn't the tax one. It's Companies House.

Miss the corporation tax payment date and HMRC charges interest. Miss the Companies House accounts deadline and you get an automatic penalty the moment you're a day late, no warning letter, no phone call, calculated on a fixed scale regardless of whether you owe any tax at all. Here's how the deadline actually works, why your very first year runs differently, and what happens if you miss it.

Your accounts are due to Companies House, separately from HMRC

Every UK limited company has an accounting reference date (ARD): the date your financial year ends. From that date, private limited companies get 9 months to file a set of statutory accounts with Companies House. This is a completely separate filing from your Company Tax Return (CT600) to HMRC, which has its own 12-month deadline, and from your corporation tax payment, which is due 9 months and 1 day after the same year end.

Three deadlines, three different rules, all measured off the same date. It's easy to see how directors conflate them, especially since the accounts deadline and the tax payment deadline land almost on top of each other but aren't the same thing and aren't owed to the same organisation.

For public limited companies, the accounts deadline is tighter: 6 months rather than 9.

Your first year works differently, and it's easy to get wrong

New companies don't get the standard 9-month rule for their first set of accounts. Instead, the deadline is 21 months from the date of incorporation, not from any accounting reference date.

This exists because a company's first accounting period is often longer than 12 months by default (Companies House sets your first ARD as the last day of the month in which your first incorporation anniversary falls, which can stretch the first period out), and the extended window accounts for that. But it also means the maths genuinely isn't "9 months after year end" for year one. A company incorporated on 15 March would have its first accounts due by 15 December of the following year, regardless of when its accounting reference date actually falls.

If you've shortened or extended your first accounting period since incorporation, this can shift again. The reliable way to check your actual deadline isn't to do the mental arithmetic yourself; it's to look up your company on the Companies House register, where your specific accounts due date is listed against your company number.

What happens if you file late

Companies House applies penalties automatically and on a fixed scale, with no discretion for "we were only a day late" or "our accountant was ill." For a private limited company:

Up to 1 month late: £150
1 to 3 months late: £375
3 to 6 months late: £750
More than 6 months late: £1,500

Public companies pay considerably more at every band, running from £750 for up to a month late to £7,500 for more than six months.

The part that catches people out twice is the repeat penalty rule: if your accounts were also late the previous year, the penalty for this year doubles. A private company that's over six months late two years running isn't looking at £1,500, it's looking at £3,000, and there's no requirement that the two late filings be for related reasons. Late is late, regardless of why.

Unlike a lot of HMRC penalties, there's very limited scope to appeal a Companies House late filing penalty on the grounds of an ordinary excuse. Companies House will consider appeals for genuinely exceptional circumstances (illness, a fire, a technical failure on their own systems), but "I forgot" or "my accountant was busy" won't get you anywhere.

It gets worse than a fine if you ignore it entirely

A late penalty is a fixed cost. Ignoring the filing altogether is a different problem. Companies House can start the process to strike your company off the register for persistent non-filing, which means the company stops legally existing, and any remaining assets can pass to the Crown. Directors of a company that's struck off for this reason can also find it affects their standing for future directorships, and in the more serious or repeated cases, non-filing can be treated as a criminal offence under the Companies Act.

None of this is likely to happen from being a week late once. It's a real risk for a company that's gone quiet on filings for a full year or more, often because whoever was meant to be tracking the deadline has left, or the business assumed the accountant had it in hand when nobody had actually been engaged.

The actual reason this catches people out

It's rarely that a director doesn't know accounts are due eventually. It's that the deadline sits nine months (or, in year one, twenty-one) after an event that isn't top of mind by the time it matters. Your financial year ends quietly, without a form to sign or an invoice to pay, and the clock starts running from a date that doesn't feel urgent until it suddenly is.

Combine that with the fact that this deadline runs on a different schedule to your corporation tax payment, and it's genuinely easy for a busy founder to track the tax bill (because HMRC chases you for that) and lose track of the accounts filing (because nobody chases you until the penalty notice arrives).

Keeping the date in view

This is exactly why FoundersLedger keeps your accounting reference date and the filings tied to it visible alongside your day-to-day bookkeeping, rather than as a date buried in a Companies House email you saw once. Knowing where you stand against the 9-month clock as you go is a lot less stressful than doing the maths for the first time when a penalty notice lands.

It doesn't replace your accountant actually preparing and filing the accounts. But it means the deadline is something you're watching, not something that finds you.

All figures correct at time of writing (August 2026) and based on current Companies House rules on annual accounts filing. This article is general information, not legal or accounting advice. Speak to your accountant about your company's specific accounting reference date and filing obligations.