Preparing to file your Company Tax Return

If you're not using an accountant, agent or tax adviser, you'll need to plan how you are going to submit online Company Tax Returns well before any filing deadlines. You'll need to make sure you keep good business records anyway, but you'll also have to enrol for the Corporation Tax Online service and choose the right software for your needs. If you are using an agent they can file your return for you and make sure that accounts and computations are properly prepared in the correct format.

This guide explains what you need to do and the options available to file your Company Tax Return.

On this page:

Who has to file a Company Tax Return?

With very few exceptions, all companies and organisations that are liable for Corporation Tax must file an online Company Tax Return. They must file their accounts and computations in a set format, Inline Extensible Business Reporting Language (iXBRL).

Overseas companies resident in the UK, or not resident in the UK but carrying on a trade here, must also complete their Company Tax Return online and file accounts and computations in iXBRL.

Companies that are part of a group must file their individual company accounts in iXBRL format. Parent companies may choose, or in certain circumstances are required, to file consolidated accounts. Where they do, these must also be in iXBRL format.

Some charities and unincorporated organisations also have to file a Company Tax Return. You can get help to decide whether your charity or organisation is liable to Corporation Tax and must file a Company Tax Return by following the links below.

Who is liable to Corporation Tax?

More on overseas companies and Corporation Tax

Read about charities and Corporation Tax

Read about unincorporated organisations and Corporation Tax


The format of the return

In very limited circumstances you may not have to file a Company Tax Return online and HMRC may accept a paper return instead. These include:

  • if the directors/company officers are all practising members of a religious society or order whose beliefs are incompatible with the use of electronic methods of communication
  • in particular situations involving insolvency - for example where your company or organisation is subject to a 'winding-up order', is in administrative receivership, or is being managed by an administrator

If you think any of these circumstances apply to you, you must contact your Corporation Tax office.

Read more about submitting your Company Tax Return in iXBLR.

Contact your Corporation Tax office


Keeping records and preparing your accounts

To file an accurate Company Tax Return you must have adequate business and accounting records. You will need to have these to hand when you file your return online. You will also need to have your full statutory company accounts prepared when you complete your return and understand accounting periods for Corporation Tax.  

You can read more about what records you need to keep and for how long in the guide to records for Corporation Tax.

You can find more information about accounting periods and when these may change by following the link below.

More about records for Corporation Tax

Read about accounting periods for Corporation Tax


Enrolling for Corporation Tax Online

If you are not using an accountant, agent or tax adviser to file your return, you will need to have enrolled for Corporation Tax Online to file the return yourself.

If you used HM Revenue & Custom's (HMRC) online registration service to tell HMRC that your limited company exists then you are automatically enrolled for Corporation Tax Online and do not need to enrol again.

If you did not use the online registration service, but instead provided all the statutory information as part of the joint incorporation service at Companies House or provided it to HMRC on paper, you will need to enroll for Corporation Tax Online separately.

Clubs and unincorporated organisations cannot use HMRC's online registration service but are still required to file their returns online.

You can read more about setting up the Corporation Tax Online service in the guide to using the service.

More about using the Corporation Tax Online service


Groups of companies: what to consider before setting up your online account

Most groups of companies will use commercial or 'in-house' software to file their Company Tax Returns online. But no matter what software you use, you must set up an HMRC Corporation Tax online account before you can file returns online.

To set up your account, you can choose one of the following options:

  • Set up and enrol each company individually for the Corporation Tax online service and file their returns individually.
  • If the group has an agent acting, but not registered for online filing, they can:
    • Get their agent to register and enrol for Corporation Tax Online and add each member of the group as a client.
    • Enrol one of the companies in the group as a 'filing only' agent for Corporation Tax Online. The agent company can then submit Company Tax Returns for all group members. This option won't allow the agent company to deal with HMRC on their behalf or use any other features of the online service.
  • If there's no tax agent or adviser already acting for the group, you can register and enrol one company as the 'agent' for the group. All other companies in the group must then be added as 'clients' by either:
    • Using the Online Agent Authorisation Service to set up the agent company authorisation. The online authorisation code necessary to complete the authorisation will be sent to each client company direct. Please ensure each company passes the code to the agent company promptly as the agent company needs to complete the online authorisation process within 30 days.
    • Completing paper forms 64-8 to authorise the agent company to deal with HMRC on their behalf.

The last option (above) allows the agent company to file returns online and use all the features of the online service for the client companies. The client companies don't have to register separately for the online service. But if you choose this option, the agent company will be treated by HMRC as the client companies' agent for all Corporation Tax matters. In particular, HMRC will send the agent company copies of computer-generated notices, assessments and other documents for the client companies.

During the registration process, you can nominate a specific person within your organisation to receive correspondence from HMRC about the online service. This includes the activation code (also known as an Activation PIN) needed to set up your Corporation Tax Online account. It's important to choose the right person to receive this correspondence to help you manage your online account effectively.

Read more on agent authorisation for Corporation Tax


Software options for filing returns

You will need to decide which software is best suited to your needs to allow you to file your Company Tax Return. You may choose to use commercially available software, ask an agent to file your return for you, or use HMRC's free software, if that is suitable.

Many companies and organisations, or their agents, use commercial software to prepare accounts, computations and file Company Tax Returns. If you are considering this it's important that you check that the software will allow you to file your return online in the right format - Inline eXtensible Business Reporting Language (iXBRL). Follow the links below to view a list of commercial software that has been tested for compatibility with HMRC's online systems and to read more about iXBRL.

Corporation Tax commercial software options

Read about submitting accounts and computations in iXBRL

Using HMRC software

Companies or organisations with straightforward tax affairs can use HMRC's free online filing software to file their return. HMRC's software can only be used to file returns for accounting periods starting on or after 1 April 2008. The software includes online templates for your accounts and computations information. If you use these templates, your accounts and computations will be attached to your online return and submitted to HMRC in the right format. The accounts template also includes a joint filing option. You can choose to enter your accounts data once and then submit that information to HMRC (as part of your Company Tax Return), and to Companies House using a 'one stop' online facility.

Using other software

If you use an integrated software package or stand-alone accounts software, your software will automatically insert the majority of the necessary iXBRL tags and produce an iXBRL accounts file. If you enter data into freeform boxes that don't have a pre-defined description and an iXBRL tag, most software includes functionality to help you identify and add the correct iXBRL tag yourself.

If you use an IT application such as Word or Excel to prepare your accounts and/or computations, you need to think about how you're going to submit them to HMRC in the right format. Software is available that will convert Word documents or Excel spreadsheets into iXBRL format. This will allow you to attach accounts and computations to your online return form in the correct format but, for this option, you'll need to understand accounting principles and have some knowledge of how XBRL works.

But no matter what software or online filing method you choose, you must ensure it's capable of submitting your company's accounts and computations to HMRC in the required format.

Who can use HMRC's Corporation Tax online filing software

Read more about the Companies House and HMRC joint filing service

Appointing someone to deal with your Corporation Tax affairs

Filing the Company Tax Return and using iXBRL


Developing your own software

If you're planning to develop your own software to meet HMRC's requirement to file returns online and pay electronically you may need more detailed help and guidance - follow the link below.

Corporation Tax - detailed guidance on online filing and electronic payment


More useful links

Read the legislation for Corporation Tax online filing