Dormant Company CT600: The 15-Minute Nil Return Guide (2026)

Yes, Your Dormant Company Still Needs a CT600

If you have a dormant limited company — one that isn't trading, has no income, and no expenses — you still need to file a Corporation Tax return with HMRC every year. This catches a lot of directors off guard.

And with HMRC's free filing service now closed (as of 31 March 2026), you need commercial software to do it. But don't worry — filing a nil return for a dormant company is quick and straightforward. This guide shows you how.

What Counts as "Dormant"?

A company is dormant for Corporation Tax purposes if it has:

• No trading income — it isn't selling goods or services
• No other income — no bank interest, no investment returns, no rental income
• No significant accounting transactions — the only permitted transactions are shares issued on incorporation and filing fees paid to Companies House

Common Scenarios

Important: "dormant" for Companies House purposes and "dormant" for HMRC Corporation Tax purposes can differ. A company can be dormant at Companies House but still need to file a CT600 if it has any income (even bank interest).

What Happens If You Don't File?

HMRC doesn't care that your company is dormant — if they expect a CT600, you must file one. If you don't:

• £100 penalty after 1 day late
• Another £100 after 3 months
• £300 or 10% of tax (whichever is higher) after 6 months
• Another £300 or 10% after 12 months

For a dormant company with no tax to pay, you'll still get the flat-rate penalties. That's £200 in penalties just for being 3 months late on a return that shows zero tax. It's not worth the risk.

HMRC can also estimate your tax liability if you don't file. They'll assume you owe tax and demand payment — and you'll need to file the return to prove otherwise.

Can You Tell HMRC Your Company Is Dormant?

Yes, and you should. If your company has stopped trading, you can notify HMRC that it's dormant. Here's what happens:

1. File your final "active" CT600 covering the period up to when trading ceased
2. Notify HMRC that the company is now dormant — call the Corporation Tax helpline (0300 200 3410) or write to them
3. HMRC may stop issuing notices to file — but this isn't guaranteed

Even if HMRC acknowledges dormancy, they can issue a notice to file at any time. If they do, you must comply.

The safest approach: file a nil return every year regardless. It takes minutes, and you'll never face an unexpected penalty.

How to File a Nil CT600 Return in 2026

With HMRC's free service gone, you need commercial software. Here's the process:

What You Need

• Company's UTR (Unique Taxpayer Reference) — 10 digits, from HMRC
• Company number — 8 characters, from Companies House
• Government Gateway user ID and password
• Your accounting period dates — start and end date of the period you're filing for

That's it. No accounts preparation, no expense tracking, no receipts. It's a dormant company.

Step-by-Step With Taxpipe

1. Create a Taxpipe account at taxpipe.co.uk
2. Add your company — enter your company number and Taxpipe pulls the details from Companies House
3. Select your accounting period — the dates your return covers
4. Indicate the company is dormant — when asked about trading activity, confirm the company had no income, no expenses, and no transactions
5. Review the return — it should show zeros across the board: zero turnover, zero expenses, zero tax
6. Generate iXBRL accounts — even dormant companies need to submit accounts. Taxpipe generates dormant company accounts automatically
7. Submit to HMRC — enter your Government Gateway credentials and submit
8. Save the confirmation — keep the HMRC receipt for your records

Total time: about 15 minutes, most of which is entering your company details for the first time. Subsequent years will be even faster.

What the Nil Return Contains

A nil CT600 for a dormant company is simple:

• Box 145 (Turnover): £0
• Box 155 (Trading profits): £0
• Box 235 (Total profits): £0
• Box 440 (Tax chargeable): £0
• Box 525 (Tax outstanding): £0

The accompanying accounts show:

• Balance sheet with share capital only (typically £1 or £100)
• No profit and loss activity
• A note confirming the company was dormant

The Accounts Requirement

This trips up many dormant company directors. Your CT600 submission to HMRC must include iXBRL-tagged company accounts, even if the company is dormant.

For dormant companies, these accounts are simple:

• A balance sheet showing share capital (and nothing else, usually)
• Notes confirming dormancy
• Directors' approval statement

You cannot just write "the company is dormant" — the accounts must be in the correct iXBRL digital format. This is one of the main reasons you need software, even for a nil return.

Taxpipe handles this automatically. When you indicate your company is dormant, it generates compliant iXBRL dormant accounts.

Dormant Company: File or Strike Off?

If you have a dormant company you never plan to use again, you have two options:

Option 1: Keep It Dormant and File Annually

Pros:

• Company name is preserved
• Ready to trade again if you want
• Quick and cheap to maintain

Costs:

• Annual CT600 nil return (software fee)
• Annual dormant accounts at Companies House (free if filing as dormant)
• Confirmation statement at Companies House (£34/year online)

Option 2: Strike Off (Dissolve) the Company

Pros:

• No more filing obligations
• No annual costs

Process:

1. File final CT600 covering the last period
2. File final accounts with Companies House
3. Apply for voluntary strike-off (form DS01, £33 fee)
4. Wait 3 months — if no objections, company is dissolved

Costs:

• One-off: software for final CT600 + £33 strike-off fee
• Then nothing, ever again

When to consider strike-off:

• You're certain you'll never trade under this company
• The company has no assets, liabilities, or outstanding obligations
• You haven't traded in the last 3 months

If you're unsure whether you'll need the company again, keep it dormant. The annual cost of filing a nil return is minimal — and much less than re-incorporating later.

Common Questions About Dormant Company CT600s

"My company has a few pounds of bank interest — is it still dormant?"

No. Any income, including bank interest, means the company has a Corporation Tax liability (even if small). You'll need to file an active return declaring the interest. Consider moving the company's funds to a non-interest-bearing account if you want to maintain dormant status.

"I forgot to file last year. What should I do?"

File immediately. The penalties accumulate, but filing stops them getting worse. If you have a reasonable excuse (serious illness, HMRC's own service causing issues), you can appeal the penalties after filing.

"Do I need to pay for software every year?"

You'll need software each time you file. With Taxpipe, you pay per filing — check our pricing for current rates. For a dormant nil return, it's the most affordable option.

"Can I file dormant accounts and CT600 at the same time?"

The CT600 goes to HMRC and your accounts go to Companies House — they're separate filings to different organisations, with different deadlines. However, some software (including Taxpipe) can help with both.

"What if HMRC hasn't sent me a notice to file?"

Even without a formal notice, if your company has an active Corporation Tax registration, HMRC expects returns. Don't assume silence means you're exempt. File proactively.

Your Dormant Company Checklist

• Check if HMRC expects a CT600 (call 0300 200 3410 if unsure)
• Note your accounting period dates
• Have your UTR and Government Gateway credentials ready
• Sign up for Taxpipe or another HMRC-approved filing tool
• File your nil CT600 with dormant accounts
• File dormant accounts at Companies House (separate process)
• File your annual Confirmation Statement at Companies House
• Set a calendar reminder for next year

Get It Done Today

A dormant company nil return is the simplest CT600 you'll ever file. Fifteen minutes and you're done for the year. Don't let it turn into a penalty because you forgot or assumed it wasn't needed.

File your dormant company CT600 with Taxpipe — we generate the nil return, create iXBRL dormant accounts, and submit everything to HMRC. Use our calculator to confirm your tax position (spoiler: it's £0).

Need to file a nil return? Taxpipe makes dormant company filing quick and painless. See our pricing for dormant company rates.