HMRC Letter About Your Dormant Company: What to Do

By Ben Davies · Updated 5 October 2026

If you're holding a brown envelope from HMRC asking about your dormant company, take a breath. These letters are common, they're rarely a sign that anything is wrong, and the fix is almost always quick and free of penalties — provided you respond.

Over the last year HMRC has been writing to thousands of dormant companies, asking directors to either re-confirm dormancy or submit a Company Tax Return (CT600). It's part of a routine review of HMRC's records. This guide walks you through exactly what the letter means and what to do next.

The most common letters HMRC sends to dormant companies

There are three letters that account for almost every "HMRC contacted me about my dormant company" panic. Identifying which one you've received tells you what HMRC actually wants.

Notice to deliver a Company Tax Return

This is the formal one. The heading usually reads something like "Notice to deliver a Company Tax Return" and quotes paragraph 3 of Schedule 18 to the Finance Act 1998. It lists an accounting period and a filing deadline (twelve months after the period end).

Once you've received this notice, you are legally required to submit a CT600 for that period — even if the company traded nothing and owes no tax. For a dormant company, that means a nil CT600, and DormantFile files it.

Dormancy review letter

This is softer. It typically says HMRC's records show your company has been dormant for some time and asks you to confirm whether the company is still dormant or has started trading. There's usually a tear-off slip or an online form referenced.

It isn't a demand for a return. Answer the question it asks, the way it asks you to. If a notice to deliver a return arrives as well, that notice still needs a return.

CT41G follow-up

The CT41G is the letter HMRC sends after a new company is incorporated, giving its Corporation Tax UTR (the company's 10-digit tax reference) and asking it to say when it becomes active. You might receive a follow-up checking whether the company is now trading. Answer the question it asks. A follow-up like this isn't a notice to deliver a return.

Don't panic — what these letters actually mean

HMRC is not accusing you of anything. The trigger for an HMRC letter dormant company review is almost always one of:

• Several years have passed since you last confirmed dormancy.
• HMRC's automated systems flagged the company for a periodic check.
• Companies House data shows the company is still active (not struck off), so HMRC wants to confirm its tax status.
• You filed dormant accounts at Companies House but HMRC's records lag behind.

None of these are red flags. They are admin. Companies House and HMRC are separate bodies with separate records — being dormant at Companies House does not automatically tell HMRC anything (see dormant vs non-trading company for why these terms diverge).

What you must not do is ignore the letter. If HMRC has issued a formal notice to deliver company tax return dormant companies must respond to, the deadline is real and penalties follow automatically once it passes.

Step 1 — Confirm the company is genuinely dormant for HMRC purposes

Before you write back, double-check that your company really is dormant in HMRC's sense. "Dormant for HMRC" is a different test from "dormant for Companies House": HMRC looks at activity and income (no trading and no income of any kind, including bank interest), while Companies House looks at whether any significant accounting transaction went through the books. The Companies House test catches more: any recorded transaction ends dormancy there, so a company can be dormant for HMRC and still not be dormant for Companies House. A company that receives income of any kind, buys or sells, or employs someone is dormant for neither.

Ask yourself:

• Has the company received any income in the period? Even bank interest counts.
• Has it paid anyone, including directors?
• Has it bought or sold anything?
• Has it issued shares, paid dividends, or settled debts?

If the answer to all of these is no, you're usually dormant for HMRC purposes. Our how to check your company is dormant guide goes into this in more detail, and our explainer on what "dormant" means under the Companies Act covers the legal definition.

If you spot any trading activity — even small — skip to Step 3, response two.

Step 2 — Gather the information HMRC needs

Whichever response you give, you'll need the following to hand:

1. The company's UTR (Unique Taxpayer Reference) — a 10-digit number HMRC sent after the company was incorporated, on a letter called a CT41G. If you can't find it, our what is a UTR number explainer shows where to look.
2. The accounting period stated in the letter — start date and end date.
3. Your Government Gateway login — the credentials you use to access HMRC online services. New to this? See what is the HMRC Gateway.
4. Confirmation that no trading occurred in the period — bank statements showing no business transactions are ideal evidence to keep on file.

You don't need an accountant to respond. A CT600 carries a copy of the company's accounts in iXBRL (a machine-readable format), and DormantFile builds that for you.

Step 3 — Answer a notice to deliver

A notice to deliver a Company Tax Return is answered with a return. Which return depends on what the company did in the period.

Response 1 — File a nil CT600

If the letter is a formal Notice to deliver a Company Tax Return and the company was dormant, you must file. Being dormant doesn't excuse it. The good news: a nil CT600 is straightforward — every figure is zero, and the return is small.

Walk through our how to file a nil CT600 guide for the exact mechanics. Our overview of what a CT600 is covers the basics if this is your first time. And if you're unsure whether you even fall into this category, do I need a CT600 for a dormant company is the right starting point.

Response 2 — Engage properly if you actually did trade

If the period in question included real trading activity — invoices, sales, paid expenses, anything — the company isn't dormant for that period. You'll need to prepare and file a normal CT600 with the underlying figures, pay any Corporation Tax due, and consider getting an accountant involved if the activity was material.

This is the only response where DormantFile isn't the right tool — we only file for dormant and non-trading companies, and every CT600 we file is nil.

When you DO need to file a nil CT600 even though dormant

This is the bit that catches people out. HMRC asking for CT600 dormant companies to file is not a mistake on HMRC's part — once a Notice to deliver has been issued, the company has a legal obligation to submit, regardless of whether tax is owed.

You must file a nil CT600 if you've received a formal Notice to deliver a Company Tax Return and the company was dormant for the period. HMRC can send one every year, even if the company is dormant at Companies House.

A confirmation slip doesn't answer a notice to deliver. The notice asks for a return.

If the company received any income in the period (including bank interest), even if expenses cancelled it out, it wasn't dormant for HMRC. Its return has to declare that income, so it isn't a nil return.

What happens if you ignore the letter

Penalties for missing a CT600 deadline are automatic:

• £200 — one day late.
• A further £200 — more than three months late (£400 total).
• 10% of unpaid tax at six months (zero for a nil return, but the £200/£400 still apply).
• A further 10% at twelve months.

Those flat rates are for a return that fell due on or after 1 April 2026. If the letter in front of you is about an older period — one whose deadline passed before that date — they are the previous £100 and £100, however late the return has since become.

After repeated non-response, HMRC can issue a determination — they estimate your tax bill, and you have to pay it unless you submit an actual return within strict time limits. Dormant companies have ended up paying hundreds of pounds in penalties simply because nobody opened the post. Penalties can be appealed — see appealing an HMRC late filing penalty for a dormant company.

The fix is almost always cheaper and quicker than the penalty. File the nil return and move on.

Let DormantFile handle the response

This is exactly what DormantFile is built for. We file the nil CT600 (and your Companies House dormant accounts in the same flow), generate the iXBRL accounts, and submit directly to HMRC and Companies House. Most directors are done in minutes, from £19/year for both filings — see how it works or check pricing. It's a calmer way out of the brown envelope.