What is an accounting reference date?

By Ben Davies · Updated 26 September 2026

Your accounting reference date (ARD) is the date your company's annual accounts are prepared to each year. It determines when your accounting period ends and, therefore, when your filings are due.

How it's set

When a company is incorporated, Companies House automatically sets the ARD to the last day of the month in which the anniversary of incorporation falls.

Example: Company incorporated on 15 June 2025. The default ARD is 30 June. Each accounting period ends on 30 June, and accounts cover the period up to that date.

You can change your ARD by filing a form with Companies House, but most dormant companies have no reason to.

Why it matters

Your ARD determines the deadlines for both filings:

• Dormant accounts to Companies House: due 9 months after the ARD (e.g., ARD of 30 June means accounts due by 31 March)
• CT600 to HMRC, when HMRC has sent a notice to deliver one: usually due 12 months after the end of the accounting period

Missing either deadline triggers automatic penalties. If you are not sure what your ARD is, search for your company on the Companies House register — it is shown on the company overview page. Plug it into our free dormant deadline calculator to get your next accounts, CT600, and confirmation statement dates in one go.

How we help

We calculate your accounts deadlines automatically from Companies House data and send reminders from 90 days before each one. CT600 accounting periods are entered by you — once added, we track and remind on their statutory deadline too, though HMRC's letter is always definitive. See how it works or check our pricing.

Read the full guide: Dormant company filing deadlines explained