Dormant company: do you still need to file a CT600?

A dormant company does not automatically need to file a CT600 every year. But if HMRC sends a notice to deliver a Company Tax Return, you must deal with it. Having no Corporation Tax to pay does not remove a filing requirement. HMRC’s Company Tax Return guidance.

The useful starting point is to check both your company’s activity and what HMRC has asked you to do.

Has HMRC asked for a return?

Read the company’s latest HMRC letters and identify the period covered by any notice to deliver a return.

HMRC’s dormant-company guidance says that if you have filed a Company Tax Return or received a notice to deliver one, you still need to file online to show the company is dormant for that period. Once you have told HMRC the company is dormant, another return is not normally needed unless HMRC issues a further notice. Read the dormant Corporation Tax guidance.

Do not treat a notice as irrelevant because your records show no sales. If you believe it was issued in error, contact HMRC promptly to resolve it.

Does no turnover mean dormant?

Check more than customer invoices. HMRC’s definition considers business activity and other income. A new company that has not started trading may be dormant; a company receiving investment income may not be. HMRC’s examples include interest, so a small bank credit deserves attention even when there have been no sales. HMRC’s trading and non-trading guidance.

A loss or a nil tax bill is a different question from whether a return is required. HMRC explicitly says a return is still needed following a notice, even where there is a loss or no tax payable. Company Tax Returns overview.

What about Companies House?

Companies House uses its own dormancy test: no significant transactions during the financial year, with specified exceptions such as incorporation share payments and Companies House filing fees.

Annual accounts and a confirmation statement remain required even when a company is dormant. A small company that meets the Companies House dormancy conditions can file dormant accounts. Companies House dormancy guidance.

Filing those accounts does not answer the separate question of whether HMRC is expecting a CT600.

What should you do next?

Work through this short checklist:

1. Check the period. Match your records to the dates on HMRC’s correspondence.
2. Review activity and income. Include bank interest and other receipts, not just sales.
3. Check notices. Identify any outstanding request for a Company Tax Return.
4. Tell HMRC where appropriate. Use its dormant-company service if the company meets the conditions.
5. Keep Companies House filings on your calendar. They remain a separate responsibility.

Keep copies of what you submit and any HMRC response. If the activity is difficult to classify, get advice on that point before choosing how to file.

If you establish that a CT600 is required, filefast can help you prepare your return for HMRC. Start your return.

Checked on 1 October 2026.

Matvei Kostiuchenko, Founder of filefast. Not an accountant. This article is general information, not a substitute for regulated tax advice.