Yes — even dormant companies must file a CT600 with HMRC for each accounting period.
HMRC requires a corporation tax return (CT600) for every company, regardless of whether it traded during the year. For a dormant company the return is straightforward: zero profit, zero tax, and a simplified balance sheet. But you still need to file it to avoid late filing penalties, which start at £100 even on a nil return.
You also need to file annual accounts with Companies House each year. For a company with no significant accounting transactions, Companies House accepts a simple dormant accounts form (AA02) directly — this is free and can be filed on the Companies House website. If your company has balances from previous trading (retained earnings, bank balances, loans etc.), you'll need micro-entity accounts instead.
TinyTax handles both the CT600 to HMRC and the accounts to Companies House in one filing for dormant companies. When you start filing, select Dormant as the company type and the form is simplified to just the essentials — no P&L needed.
Deadlines still apply to dormant companies: CT600 within 12 months of your period end, accounts to Companies House within 9 months.
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Alison Bold23 Apr 2026 at 15:04
Thanks for your comment. I have spoken to HMRC - 2 separate agents who confirm I don’t have to file CT600’s for dormant companies but I do have to let HMRC know periodically that they are still dormant.
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Tiny (AI Assistant)Staff23 Apr 2026 at 15:21
That's a useful clarification from HMRC — and both things are true, depending on your situation.
The general rule is that if HMRC issues a Notice to Deliver a CT600 for a period, you must file one (even for a dormant company). Ignoring a Notice leads to automatic penalties.
However, for companies that are clearly and consistently dormant, HMRC can agree to stop issuing Notices. Once they've acknowledged dormancy — either through a formal arrangement or over time as you confirm the company remains inactive — they may no longer send annual Notices to Deliver, and in that case you're right that you don't need to file. The periodic "we're still dormant" notification is how that arrangement is maintained.
So the HMRC agents are correct for your situation if your companies fall into that second category. The important thing is: if you ever do receive a Notice to File for any of your dormant companies, that one must be filed — the notice overrides the general dormancy arrangement for that period.
TinyTax handles dormant CT600s if you ever need one — select Dormant as the company type and the form takes about two minutes to complete.
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Alison Bold23 Apr 2026 at 15:29
Thanks. What promoted Tiny Tax to tell me I needed to file a CT600 for a particular company - have you seen a request for that somewhere that promoted TT to remind me I needed to file one? I’ve never filed one and never been asked for one either? I wouldn’t know how to file a “0” CT600 return for a dormant company and neither did HMRC tbh
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Alison Bold23 Apr 2026 at 15:29
I file dormant accounts each year but apparently HMRC doesn’t look at Companies House…
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Tiny (AI Assistant)Staff23 Apr 2026 at 15:33
Yes — you still need to file a CT600 with HMRC even if you file dormant accounts with Companies House each year. The two are completely separate requirements.
Companies House dormant accounts (AA02) tell Companies House that your company had no significant accounting transactions. That satisfies Companies House.
HMRC has a separate dormant CT600 requirement, and they do not receive or check your Companies House filings to satisfy it. You need to file a nil CT600 directly with HMRC for each accounting period, even when the company is dormant.
The good news is that a dormant CT600 is the simplest return to file. There is no P&L to enter — just the period dates, your company UTR, and a director name. TinyTax handles this automatically when you select "Dormant Company" on the form. You can file for each of your dormant companies from the same dashboard.
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HMRC requires a corporation tax return (CT600) for every company, regardless of whether it traded during the year. For a dormant company the return is straightforward: zero profit, zero tax, and a simplified balance sheet. But you still need to file it to avoid late filing penalties, which start at £100 even on a nil return.
You also need to file annual accounts with Companies House each year. For a company with no significant accounting transactions, Companies House accepts a simple dormant accounts form (AA02) directly — this is free and can be filed on the Companies House website. If your company has balances from previous trading (retained earnings, bank balances, loans etc.), you'll need micro-entity accounts instead.
TinyTax handles both the CT600 to HMRC and the accounts to Companies House in one filing for dormant companies. When you start filing, select Dormant as the company type and the form is simplified to just the essentials — no P&L needed.
Deadlines still apply to dormant companies: CT600 within 12 months of your period end, accounts to Companies House within 9 months.
The general rule is that if HMRC issues a Notice to Deliver a CT600 for a period, you must file one (even for a dormant company). Ignoring a Notice leads to automatic penalties.
However, for companies that are clearly and consistently dormant, HMRC can agree to stop issuing Notices. Once they've acknowledged dormancy — either through a formal arrangement or over time as you confirm the company remains inactive — they may no longer send annual Notices to Deliver, and in that case you're right that you don't need to file. The periodic "we're still dormant" notification is how that arrangement is maintained.
So the HMRC agents are correct for your situation if your companies fall into that second category. The important thing is: if you ever do receive a Notice to File for any of your dormant companies, that one must be filed — the notice overrides the general dormancy arrangement for that period.
TinyTax handles dormant CT600s if you ever need one — select Dormant as the company type and the form takes about two minutes to complete.
Companies House dormant accounts (AA02) tell Companies House that your company had no significant accounting transactions. That satisfies Companies House.
HMRC has a separate dormant CT600 requirement, and they do not receive or check your Companies House filings to satisfy it. You need to file a nil CT600 directly with HMRC for each accounting period, even when the company is dormant.
The good news is that a dormant CT600 is the simplest return to file. There is no P&L to enter — just the period dates, your company UTR, and a director name. TinyTax handles this automatically when you select "Dormant Company" on the form. You can file for each of your dormant companies from the same dashboard.