Dormant company filing guides

Plain-English answers on dormant company filing, written for company directors rather than accountants. Everything here is grounded in gov.uk guidance, with sources linked at the end of each guide.

Dormant companies

Do dormant companies need to file a CT600?

When a dormant company must still file a Company Tax Return, and when it does not.

Is my company dormant? A five-question check

Separate answers for Companies House and HMRC, because they do not agree.

Dormant for Companies House vs dormant for Corporation Tax

The two regulators define dormant differently, and each has its own filings.

How to tell HMRC your company is dormant

Notify HMRC of dormancy, and when that means no CT600 is needed at all.

Dormant company with money in the bank

Cash, a director's loan or share capital do not stop a company being dormant. How the return looks.

Bank interest and dormant companies

Even a few pounds of interest changes the answer for HMRC. What to file instead.

Dormant company iXBRL accounts explained

Why HMRC requires tagged accounts inside the return, and how they are produced.

Late CT600 penalties for dormant companies

The penalty ladder applies even when no tax is due.

Closing a dormant company: strike-off and the final return

The DS01 route, the three-month rule, and whether HMRC still wants a last CT600.

Filing a CT600

HMRC's free filing service has closed: your options

What the closure on 31 March 2026 means and how dormant companies file now.

How to file a dormant company CT600 online

Step by step: what you need, what gets filed, and what happens after.

CT600 rejected by HMRC: what the error codes mean

1046, 1608, 3001, 3304 and the rest: what each one means and what to do next.

Enrol for Corporation Tax online before you file

Adding Corporation Tax to your Government Gateway account, and the activation code wait.

Find or recover your Government Gateway user ID and password

Where the ID is written down, how recovery works, and what to do when the account was an old accountant's.

Company UTR vs personal UTR: find the right one for a CT600

Both are 10 digits. How to tell them apart, where the company's appears, and why the wrong one gives a sign-in error.

The CT603 notice to deliver a Company Tax Return

The letter that makes a CT600 due, what it says, and the deadline it sets.

Your first Company Tax Return: why HMRC expects two CT600s

A first accounting period longer than 12 months means two returns, not one.

CT600 deadline calculator

Enter your accounting period end date and get every HMRC and Companies House deadline.

The cheapest way to file a CT600: options compared

Accountant, general software or a dormant-company specialist: an honest comparison.

Does my small charity need to file a CT600?

A charity only files when HMRC asks. What is exempt, what page CT600E wants, and why no tax computation is needed.

Company traded, loss or small profit: what to file

A company that traded owes a full return with a tax computation, with or without tax to pay. What we can file for £15, and where to go otherwise.