Who must sign a company tax return

Q: How might this look in practice?

Illustration only. Brook Design Ltd has two directors and no secretary. Its accountant prepares the accounts, computations and CT600, then sends a draft pack to the finance director, who reviews the R&D claim and signs a short approval stating the return is correct and complete to the best of her knowledge. Because the accountant prepared and filed the return, the accountant makes the declaration on the CT600 and keeps the signed approval on file. The following year the company enters creditors' voluntary liquidation before the return is filed. The directors can no longer approve or sign it. The liquidator, as proper officer, decides what to submit for the pre liquidation period and makes the declaration.

A company tax return must include a declaration by the person making it that the return is correct and complete to the best of their knowledge. The company acts through its proper officer (the company secretary, or a liquidator or administrator once appointed) or, unless a liquidator is in office, through anyone else with authority to act for it, which in most small companies means a director. An accountant can make the declaration only where the accountant both prepares and submits the return.

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What exactly is being declared on a CT600?

The duty comes from paragraph 3 of Schedule 18 to the Finance Act 1998. Paragraph 3(1) lets HMRC require a company, by notice (form CT603), to deliver a return, and paragraph 3(3) says that the return must include a declaration by the person making it that the return is, to the best of their knowledge, correct and complete.

On the form itself the declaration is at boxes 975 (name of the person making the declaration), 980 (date) and 985 (status, such as director or company secretary). HMRC’s Company Tax Return guide points out that completed supplementary pages form part of the return and are covered by the declaration, so whoever signs is vouching for the CT600A loans page, the group relief page or the R&D page as well as the main form. The return as a whole also includes the accounts and the tax computations; see the CT600 return explained for the full package.

Who is the proper officer of a company?

Section 108 of the Taxes Management Act 1970 says everything a company has to do under the Taxes Acts is done by the company acting through its proper officer. Section 108(3) defines that person:

for a company that is a body corporate, the secretary or the person acting as secretary;
if a liquidator or administrator has been appointed, the liquidator or administrator instead;
for a body that is not incorporated, such as a club or association, or where there is no proper officer under the first rule, the treasurer or the person acting as treasurer.

HMRC’s Company Tax Return obligations guidance confirms that, for the filing duty, a company includes members’ clubs, associations, societies and other unincorporated bodies, so the treasurer rule has real practical use.

Many companies have no secretary at all. Section 270(1) of the Companies Act 2006 says a private company is not required to have one. That is why the second limb of section 108(1) is so important for small companies.

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Can a director sign instead of the secretary?

Yes. Section 108(1) allows the company to act through the proper officer or, except where a liquidator has been appointed, through any other person who for the time being has the express, implied or apparent authority of the company to act on its behalf. Those words were inserted with effect from 27 July 1993. A director who runs the company’s finances will normally have that authority, and so will a finance manager whom the board has authorised to deal with tax.

The safest practice is for the board to know who will sign and to have seen the final figures. A director who makes the declaration should have read the return, not just the accounts, because the CT600 contains claims and elections that do not appear anywhere in the accounts.

When can an accountant make the declaration?

HMRC’s Company Tax Return obligations guidance sets out three situations:

If the company completes and submits its own return, the declaration is made by the person making it on behalf of the company.
If a tax agent completes and submits the return, the declaration must be completed by that agent.
If a tax agent only submits the return for the company, the declaration must be made by the proper officer or another person authorised to act for the company.

In the third case, before submitting, the agent must make a copy of the information and receive confirmation from the proper officer or other authorised person that it is correct and complete to the best of that person’s knowledge and belief. In practice most firms obtain a signed approval of the return and computations from a director before filing, whichever case applies, because it is the evidence that the company authorised what was sent.

Who signs once a company is in liquidation or administration?

The appointment of an insolvency practitioner changes the answer. Under section 108(3)(a) a liquidator or administrator becomes the proper officer. HMRC’s manual at COM130050 adds that a liquidator becomes the only person through whom the company can act for any purpose under section 108(1); the directors’ general authority to act for the company on tax does not survive a liquidation. Where two or more administrators act jointly, section 108(4) says the proper officer is the one named in a notice they give to HMRC or, without a notice, whichever of them HMRC designates.

COM130050 also recognises that a full return is often impossible in a formal winding up because accounts for periods before the appointment are never prepared, and says HMRC should take a pragmatic approach to what insolvency practitioners submit. See corporation tax in liquidation and corporation tax in administration for the wider rules.

What happens if a return is not properly authorised?

HMRC’s view at CTM93260 is that a document that fails to meet the statutory requirements of paragraph 3 is not a return at all, so the company has not met its obligation and may be liable to penalties under paragraphs 17 and 18 of Schedule 18. CTM93270 tells staff to send a paper return back if the CT600 has not been signed. For online filing, CTM93260 explains that the Government Gateway user ID and password provide the authentication HMRC relies on to accept the authority of a return, and that HMRC should now only exceptionally treat a return as unsatisfactory.

The bigger risks are about who answers for errors:

Under paragraph 18 of Schedule 24 to the Finance Act 2007, the company is liable for a careless inaccuracy in a document given to HMRC on its behalf, but not for something done or omitted by its agent if it satisfies HMRC that it took reasonable care.
Under paragraph 19, where a company is liable for a deliberate inaccuracy attributable to an officer, HMRC can make that officer pay a portion of the penalty, up to 100%. For a company, officer means a director (including a shadow director), a manager or a secretary.
HMRC’s guidance warns that providing false information or concealing profits or tax payable can lead to prosecution of both the individual and the company.

A director who signs without reading the return will struggle to show reasonable care. See company officers’ liability for penalties.

How might this look in practice?

Illustration only. Brook Design Ltd has two directors and no secretary. Its accountant prepares the accounts, computations and CT600, then sends a draft pack to the finance director, who reviews the R&D claim and signs a short approval stating the return is correct and complete to the best of her knowledge. Because the accountant prepared and filed the return, the accountant makes the declaration on the CT600 and keeps the signed approval on file.

The following year the company enters creditors’ voluntary liquidation before the return is filed. The directors can no longer approve or sign it. The liquidator, as proper officer, decides what to submit for the pre liquidation period and makes the declaration.

What mistakes come up most often?

A former director, or a director who has resigned, approving the return.
Directors continuing to deal with HMRC after a liquidator is appointed.
An agent who only files the return making the declaration itself, instead of obtaining it from the company.
No written evidence that the company approved the figures before filing.
Signing without reading the supplementary pages, which are covered by the same declaration.
Assuming a later correction fixes everything; an amendment has its own time limit, see amending a CT600.

The way a director signs contracts raises separate questions of personal liability; see signing as a director without personal liability.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.