HMRC's company tax return service has closed: how to file now

When did HMRC's company tax return service close?

HMRC's company tax return service closed on 31 March 2026. GOV.UK says: "The 'File your accounts and Company Tax Return' online service closed on 31 March 2026." From 1 April 2026, HMRC says you should use commercial software to file annual accounts and Company Tax Returns with HMRC.

The closure changes how you file, not whether you file. If HMRC has sent your company a notice to deliver a Company Tax Return, the return is still due.

Source: Filing company accounts and tax returns if you previously used the HMRC online service

What do you need to file a Company Tax Return now?

You need commercial software that can file with HMRC, or an agent who files for you. HMRC publishes a list of commercial software suppliers for Corporation Tax. GOV.UK says the suppliers on it have given evidence that their software or service can produce one or more elements of a Company Tax Return.

Before you choose, check the product does everything your company needs. GOV.UK says to make sure the software lets you file:

• a CT600, the Company Tax Return form
• a Corporation Tax computation
• your company accounts

Source: Filing company accounts and tax returns if you previously used the HMRC online service

How to use HMRC's software suppliers list

For each product, HMRC's list shows whether it can produce and submit a CT600, whether it can submit iXBRL documents, and whether it is suitable for self-filers. iXBRL is the tagged format used for accounts and computations sent with the return.

HMRC says it cannot recommend or endorse any one product over another, and it cannot give support for them. Questions about a product go to its supplier. We do not recommend products either. Check prices and what is included with each supplier directly.

Some products on the list can file your Company Tax Return and your annual accounts together. Others only cover part of the job, so check before you buy.

Source: List of commercial software suppliers for Corporation Tax

Can you file a CT600 without an accountant?

Yes. You can file a CT600 without an accountant: GOV.UK says you can either get an accountant to prepare and file your Company Tax Return or do it yourself. Since the HMRC service closed, doing it yourself means using commercial software, and HMRC's list marks which products are suitable for self-filers.

When you file, you work out the company's profit or loss for Corporation Tax and its Corporation Tax bill. GOV.UK points out that this profit or loss is different from the one in your annual accounts, so the computation matters.

Source: Company Tax Returns

Can you still file a paper Company Tax Return?

You can only file a paper Company Tax Return in limited cases. GOV.UK says you can file a paper return with HMRC if you have a reasonable excuse or are filing in Welsh. Otherwise, you must file online, using commercial software or an agent. HMRC's online service is no longer an option.

Source: Filing company accounts and tax returns if you previously used the HMRC online service

Your accounts still go to Companies House separately

HMRC's closure guidance says you need to continue to file annual accounts with Companies House. You can file them online with Companies House or send paper accounts by post. That is a separate filing with its own deadline.

If your company is dormant for Companies House, you may be able to file dormant company accounts. For trading or micro-entity accounts, use the official Companies House filing route or speak to an accountant.

Source: File your company's annual accounts with Companies House

What should a dormant company do?

A dormant company that has had a notice to deliver a Company Tax Return still has to file it. GOV.UK says: "You'll still need to file a Company Tax Return online - this will show HMRC that your company is dormant for this period." With the HMRC service closed, that return also goes through commercial software or an agent.

Once you have told HMRC the company is dormant, GOV.UK says you do not need to file another Company Tax Return unless you receive a further notice. For the full picture, see does a dormant company file a CT600.

Source: Dormant companies: dormant for Corporation Tax

The deadlines have not changed

The closure did not move any deadlines. The Company Tax Return is still due 12 months after the end of the accounting period it covers. Corporation Tax is usually due 9 months and 1 day after the end of the accounting period, which is before the return is due.

Late filing penalties still apply. See the Company Tax Return deadline and penalties and when Corporation Tax is due for the detail.

Source: Company Tax Returns

Amending an earlier return or re-filing a rejected one

If you want to change a return you already submitted, or re-file a rejected return, GOV.UK lists these options:

• use commercial software
• write to, or send a paper return to, the Corporation Tax office
• use an agent

Source: Filing company accounts and tax returns if you previously used the HMRC online service

When can you still amend a Company Tax Return?

You must usually amend a Company Tax Return within 12 months of the filing deadline. GOV.UK says that after that, you may still be able to claim back overpaid Corporation Tax through overpayment relief, and you should tell HMRC about underpaid Corporation Tax using the online disclosure service as soon as possible.

HMRC's closure guidance adds that to change or correct accounts already filed with Companies House, you need to use software or send paper accounts by post.

Source: Company Tax Returns: making changes

Where SimpleFilings fits

SimpleFilings does not prepare or file Company Tax Returns or recommend software. We can help with the paperwork around them for a £4.99 SimpleFilings service fee per filing: requesting a copy of the company's UTR, telling HMRC the company is dormant, preparing and filing qualifying dormant accounts. The total price includes applicable government filing fees. Penalties are separate.