First year filing for a new dormant company

By DormantFile · Updated 28 March 2026

You have just incorporated a company and it is going to sit dormant. Here is what you need to file, and when.

If you'd rather see your three first-year dates instantly, plug your incorporation date into the free dormant deadline calculator — it applies the 21-month rule automatically.

The three filings

Every UK limited company, including dormant ones, has three regular filing obligations:

1. Annual accounts (Companies House)

Your first accounts cover the period from incorporation to your first accounting reference date (ARD).

Default ARD: The last day of the month in which the anniversary of incorporation falls. For a company incorporated on 15 March 2026, the default ARD is 31 March 2027. The first accounting period runs from 15 March 2026 to 31 March 2027.

First-year deadline: Because your first accounting period runs longer than 12 months (the default, unless you shorten it), your first accounts are due 21 months from the date of incorporation — not 9 months after the period end, as in later years. Strictly, the law allows 3 months after the period end if that is later, but with a normal first period it never is.

Watch the trap: for the 15 March 2026 company above, that means a deadline of 15 December 2027 — about two weeks earlier than "9 months after 31 March 2027" would suggest. Diarise the 21-month date.

For dormant accounts, you will file dormant company accounts confirming no significant accounting transactions. We walk through the process in our guide on how to file dormant company accounts.

2. Confirmation statement (Companies House)

A confirmation statement (CS01) must be filed at least once every 12 months from the date of incorporation. This confirms your company's details: registered office address, directors, shareholders, and SIC codes.

The filing fee is £50 online or £110 paper.

This is separate from annual accounts and has its own deadline.

3. CT600 (HMRC) — only if registered for Corporation Tax

If your company is registered for Corporation Tax, you need to file a nil CT600 within 12 months of the end of the accounting period.

Not every new dormant company will be registered. If you incorporated but never notified HMRC, you may not need a CT600 at all. We cover how to check in our guide on whether you need a CT600.

Since CATO closed on 31 March 2026, there is no free way to file a CT600 directly with HMRC. You will need commercial software or an accountant.

Example timeline

Company incorporated: 1 June 2026

Credentials you will need

The two filings require different credentials:

• Companies House accounts: Your Companies House authentication code — a 6-character alphanumeric code sent to your registered office. Request it from Companies House if you do not have one.
• HMRC CT600: Your UTR number and HMRC Government Gateway user ID and password.

Tips for first-year filing

• Do not panic about the first accounts deadline. The 21-month rule means you have plenty of time — just diarise 21 months from incorporation, not 9 months after the period end.
• Do file your confirmation statement on time. This is the first filing that comes due — typically 12 months after incorporation.
• Check your Corporation Tax status. If you are not registered, you do not need a CT600. If unsure, call HMRC on 0300 200 3410.
• Set up reminders. We calculate all deadlines automatically in DormantFile and send email reminders so deadlines stay on your radar. See how it works.

Key points

• New dormant companies need: accounts (Companies House), confirmation statement (Companies House), and possibly CT600 (HMRC).
• First accounts deadline: 21 months from incorporation when the first period runs longer than 12 months (the default).
• Confirmation statement: due within 12 months of incorporation, £50 online / £110 paper.
• CT600: only if registered for Corporation Tax, due 12 months after period end.
• Late filing penalties apply to dormant companies just as they do to trading ones.