Yes, Dormant Companies Must File a CT600
One of the most common misconceptions among company directors: "My company didn't trade, so I don't need to file." Wrong. HMRC requires a CT600 from every registered company, trading or not.
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?
HMRC doesn't care that your company is dormant — if you don't file, you get penalties:
| Late by | Penalty |
|---|---|
| 1 day | £100 |
| 3 months | Another £100 |
| 6 months | 10% of unpaid tax (minimum £300) |
| 12 months | Further 10% of unpaid tax |
Since a dormant company owes £0 in tax, the 10% penalties don't bite. But you'll still get the flat £100 + £100 = £200 in penalties for filing more than 3 months late. For a company that owes nothing.
Don't waste £200. 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
- That's it
What to Put in the Boxes
For a dormant company, almost everything is zero:
| Box | Description | Value |
|---|---|---|
| 145 | Total turnover | 0 |
| 155 | Trading profits | 0 |
| 235 | Charges paid | 0 |
| 315 | Total profits | 0 |
| 430 | Corporation tax | 0 |
| 515 | Tax payable | 0 |
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. 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. You can notify HMRC that your company is dormant, and they may stop sending CT600 notices. But:
- This doesn't always work — HMRC sometimes keeps sending reminders
- If your company becomes active again, you must notify HMRC immediately
- It's safer to just file the nil return each year
Filing takes 15 minutes. Missing a filing takes hours to sort out with HMRC. Just file.
What About Companies House?
Separate obligation. You also need to file:
- Confirmation Statement (annual, £13 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 (£33 fee) using form DS01.
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
- Sign up at taxpipe.co.uk
- Enter your company details (CRN and UTR)
- Select "Dormant company"
- Review the auto-generated nil return
- Submit to HMRC
- Done — £59, 15 minutes
No accountant needed. No iXBRL headaches. No penalties.