Dormant Company CT600 — How to File a Nil Return

Do Dormant Companies Have to File a CT600?

One of the most common misconceptions among company directors: "My company didn't trade, so I don't need to file." Not so fast. If HMRC has sent your company a notice to deliver a Company Tax Return (form CT603), you must file a CT600 — even if the company did absolutely nothing all year. And HMRC issues those notices automatically unless you've told them the company is dormant and they've agreed to stop.

The good news? A dormant company CT600 is simple. Most boxes are zero. The whole process takes about 15 minutes.

What Counts as a Dormant Company?

For corporation tax purposes, a company is dormant if it:

• Has no income (no sales, no interest, no investment income)
• Has no expenses to speak of (a small bank fee doesn't necessarily make you active)
• Is not trading in any form

Common dormant company scenarios:

• A company set up but never used
• A company that stopped trading but hasn't been dissolved
• A holding company that exists but does nothing
• A company waiting to start trading

Important: If your company earned even a small amount of bank interest, it's technically not dormant for CT purposes. You'd need to declare that income.

What Happens If I Don't File?

If HMRC has asked for a return, they don't care that your company is dormant — if you don't file, you get penalties. For returns with a filing date on or after 1 April 2026:

(For returns whose filing date fell before 1 April 2026, the flat penalties were £100 and £100 — HMRC doubled them from April 2026. File late three accounting periods in a row and the flat penalties rise to £1,000 each.)

Since a dormant company owes £0 in tax, the 10% tax-geared penalties don't bite — there's no fixed minimum for corporation tax. But you'll still get the flat £200 + £200 = £400 in penalties for filing more than 3 months late. For a company that owes nothing.

Don't waste £400. File the nil return.

How to File a Dormant CT600

What You Need

• Company Registration Number (CRN) — 8 digits
• Unique Taxpayer Reference (UTR) — 10 digits from HMRC
• Accounting period start and end dates
• A Government Gateway account enrolled for Corporation Tax
• That's it

What to Put in the Boxes

For a dormant company, almost everything is zero:

Your software should handle this automatically. Taxpipe has a dormant company shortcut — select "dormant" and it auto-zeros everything and skips straight to review.

Accounts

Even dormant companies need to include accounts with their CT600. For a dormant micro-entity, these are minimal:

• A balance sheet (usually just share capital of £1 or £100)
• A profit and loss account (all zeros)
• A note confirming the company was dormant

Filing software generates the iXBRL accounts for you.

Submit

File through HMRC-recognised software using your own Government Gateway credentials. The submission goes through the same process as an active company — XML validation, iXBRL check, HMRC acknowledgement.

Can I Tell HMRC My Company Is Dormant?

Yes — and it's worth doing. Once you notify HMRC that your company is dormant and they accept it, they stop issuing notices to deliver a return, and no CT600 is due unless and until they issue one. A few things to keep in mind:

• The exemption only applies once HMRC has confirmed it — if a notice to deliver has already been issued for a period, you still need to file for that period
• If your company becomes active again, you must tell HMRC within 3 months of starting to trade
• HMRC may still ask for a return from time to time — if a notice arrives, file, even if the company stayed dormant

Filing a nil return takes 15 minutes. Ignoring a notice to deliver takes hours to sort out with HMRC — and racks up penalties. If they've asked, just file.

What About Companies House?

Separate obligation. You also need to file:

• Confirmation Statement (annual, £50 online)
• Dormant accounts (annual, free to file)

Missing Companies House filings can lead to your company being struck off the register.

Should I Just Dissolve the Company?

If you're sure you'll never use the company again, dissolving it stops all filing obligations. You can apply to Companies House to strike off your company using form DS01 — £13 online, or £18 on paper.

But keep the company if:

• You might trade again in future
• You want to keep the company name
• There are assets in the company (even just a bank account with a balance)

Filing Your Dormant CT600 with Taxpipe

1. Sign up at taxpipe.co.uk
2. Enter your company details (CRN and UTR)
3. Select "Dormant company"
4. Review the auto-generated nil return
5. Submit to HMRC with your Government Gateway credentials
6. Done — £59, 15 minutes

No accountant needed. No iXBRL headaches. No penalties.

File your dormant company CT600 now →