Does a dormant company need to file a CT600?

It depends. If HMRC considers your company active for corporation tax purposes, you must file a CT600 even if the company is dormant at Companies House. You can tell HMRC the company is dormant to stop receiving notices to file.

What is a nil CT600 return?

A nil CT600 return is a corporation tax return showing zero income, zero expenses, and zero tax due. Dormant companies that are still required to file with HMRC submit nil returns until they notify HMRC of dormancy.

How do I tell HMRC my company is dormant?

You can write to your HMRC Corporation Tax office or call the CT helpline to inform them the company is dormant and has no corporation tax liability. Once HMRC accepts this, they will stop issuing notices to file CT600 returns.

Guide · February 2026

Dormant Company CT600: Do You Still Need to File?

Thousands of UK limited companies are dormant — no trading, no income, no expenses. But HMRC still expects to hear from most of them. Here is what you actually need to do.

What counts as dormant?

HMRC and Companies House use slightly different definitions:

•Companies House: A company is dormant if it has had no "significant accounting transactions" during the financial year. Filing fees and shares on formation do not count.
•HMRC: A company is dormant for Corporation Tax if it is not active — not carrying on business and not receiving any income.

A company can be dormant for Companies House but not for HMRC (for example, if it earns bank interest on a deposit). The reverse is rarer but possible.

Do you need to file a CT600?

Short answer: it depends on whether HMRC considers you dormant.

If your company has never traded since incorporation, or you have told HMRC it is dormant and they have confirmed it, then HMRC will not issue a "notice to deliver" and you do not need to file a CT600.

However, if your company previously traded and has since gone dormant, you must:

File a final CT600 covering the period up to when trading stopped
Tell HMRC the company is now dormant (write to your Corporation Tax office or call the CT helpline)
Wait for HMRC to confirm they have made the company dormant in their records

Until HMRC confirms dormancy, they may continue issuing notices to deliver — and you must file or face penalties.

How to file a nil CT600

If HMRC has issued a notice to deliver for a dormant period, you file a CT600 with zeros. This is sometimes called a "nil return." The steps:

Enter your company details and accounting period
Put £0 for turnover, costs, and all other figures
Corporation tax will calculate as £0
Submit to HMRC as normal

You still need to file accounts with Companies House. Dormant companies can file simplified dormant accounts (form AA02) — no profit and loss account is needed, just a basic balance sheet.

After April 2026

From 1 April 2026, HMRC will close its free online CT600 filing portal. If your dormant company still receives notices to deliver, you will need commercial software to file your nil return.

Taxentis handles nil returns — enter zeros, generate the CT600 XML, and submit to HMRC. No spreadsheets, no paper forms.

Can you strike off a dormant company instead?

If you do not plan to use the company again, striking it off (dissolving it) removes the filing obligations entirely. You can apply to Companies House using form DS01 if:

•The company has not traded in the last 3 months
•It has not changed its name in the last 3 months
•There are no outstanding debts, charges, or legal proceedings

The fee is £33 online. You must still file any outstanding CT600 returns and accounts before or during the strike-off process.

File your dormant CT600 with Taxentis

Need to file a nil return? Taxentis makes it painless — look up your company, enter zeros, and submit directly to HMRC.

File your CT600