Using Corporation Tax Online

Please note: if you use or plan to use an accountant, agent or tax adviser to file your Company Tax Return, then your agent must be authorised to use Corporation Tax Online on your behalf  

This guide will give you an overview of HM Revenue & Customs' (HMRC's) Corporation Tax Online, including setting up an online account and enrolling for the service - if you aren’t enrolled already - and what the service offers.

On this page:

Corporation Tax Online - an overview

You can use Corporation Tax online to:

  • file your Company Tax Return to HMRC over the internet using HMRC's free online filing software or commercially available software
  • file your statutory, abbreviated or dormant accounts to Companies House over the internet
  • change an accounting period
  • amend a Company Tax Return you've already submitted to HMRC
  • view your Corporation Tax liabilities and payments
  • change your company or organisation's details - for example your contact address
  • add, change or remove your accountant or authorised agent


Enrolling for Corporation Tax Online

Most limited companies that are active at the time they register at Companies House use the Companies House online joint registration service to supply additional statutory information to HMRC. Alternatively, you may have supplied this information to HMRC on paper. In both these circumstances you will need to sign up and enrol for Corporation Tax Online to file your return online. Follow the link immediately below to do this now.

Enrol for Corporation Tax Online

If you weren't able to - or chose not to - send some or all of the information you are required to tell HMRC using the Companies House service, you can use HMRC's online registration service to do this now. If you use this service, you are automatically enrolled for Corporation Tax Online and do not need to enrol separately. If you wish to use the service to send the additional statutory information to HMRC, follow the link below for more information.

Please note: You must have a separate Government Gateway account (User ID and Password) for each company that you want to register with HMRC for Corporation Tax. This will allow HMRC to automatically enrol the company for CT Online once your registration application has been processed.

Register for HMRC taxes and sign up for online services

If you run a club or other organisation that has to file a Company Tax Return, you have to file your return online. To do this you must have enrolled for Corporation Tax Online.

Sign up for an HMRC online account and the Corporation Tax Online Service as a new user

Login to your existing HMRC online account

If you are already set up for HMRC Online services

If you're already set up as a company or unincorporated organisation for other HMRC online services - such as PAYE for Employers or VAT - you can easily add Corporation Tax Online to your existing account. To do this:

  1. Log in to HMRC Online services with your existing User ID and password.
  2. On the 'Your HMRC Services' page under the 'Services you can add' section, select 'Corporation Tax (CT)' and 'Enrol for service'.
  3. Enter information about the company or organisation - see the 'Before you get started' section above. On-screen instructions will guide you through the enrolment process

Log in to HMRC Online services


Filing your Company Tax Return

You can file your return online using HMRC's free online filing software, commercially available software, or software you've developed or had developed for you. Commercial software or your own software may offer greater flexibility for your company.

Using HMRC's free software

HMRC's online filing software - which is a downloadable PDF - is aimed at smaller companies and organisations with straightforward financial affairs.

After you've downloaded HMRC's online filing software, you'll need to change some computer settings on Adobe Reader to allow you to use all the features of the software and send your data safely to HMRC.

Read HMRC guidance on changing Adobe Reader settings

Once you've done this, you can use HMRC's software to file:

  • CT600 (Short) return form
  • supplementary page CT600A (Loans to Participators by Close Companies)
  • supplementary page CT600E (Charities and Community Amateur Sports Clubs)
  • supplementary page CT600J (Disclosure of Tax Avoidance Schemes)

HMRC's software also includes:

  • Templates that automatically allow you to file your company accounts and computations in the right format, as part of your Company Tax Return.
  • A joint filing option for company accounts. You can choose to enter your company accounts information once and then submit that information to HMRC as part of your Company Tax Return, and to Companies House.
  • An option to attach your own accounts and computations to the HMRC online CT600 form in the required format if you don't use the templates provided.
  • A facility to attach other relevant items that are required as part of your return, for example claims or elections, reports and statements, in PDF format.
  • Built-in automatic calculations and checks that leave less room for mistakes and there's on-screen help to guide you as you work through it.
  • A facility to store your return on your own system and print out a copy for your records.

Micro entity companies

HMRC’s filing software allows the smallest companies to choose to prepare and publish simplified financial statements (profit & loss account and balance sheets) if they meet 2 or more of the following criteria:

  • turnover £632,000 or less
  • balance sheet where assets total £316,000 or less
  • number of employees < 10

Follow the links below to find more information about who can use HMRC's software and a beginner's guide to using it to file your Company Tax Return.

Who can use HMRC's Corporation Tax online filing software

Filing your Company Tax Return online: a beginner's guide (PDF 2MB)

Using commercial software

Commercial software may be better suited to your company or organisation's circumstances as it generally offers greater flexibility and choice of Company Tax Return supplementary pages. If you do choose commercial software, you'll need to check with your supplier that it meets the HMRC requirement to produce accounts and computations in iXBRL format.

HMRC provides a validation service to help software companies test their products. If they're successful, HMRC adds them to its list of successfully tested software packages.

Find out more about HMRC-tested commercial Company Tax Return software

What counts as the date the return is received?

As soon as the HMRC computer system receives your online return, it automatically records the date received. You will be given confirmation on screen that you have been successful in sending your return to HMRC, including the date and time of receipt. The screen will also include a unique submission receipt reference number. HMRC recommends that you keep a copy of your saved submitted return and submission receipt reference number.

Please note: confirmation that you have successfully sent your return to HMRC is not confirmation that HMRC has ‘accepted' or 'examined and agreed' your return.


Amending a Company Tax Return you've already filed

You can use HMRC's online filing software to amend your Company Tax Return. You can do this whether you submitted the original return using HMRC's own filing software or commercial software, or even if (by exception) you sent it to HMRC on paper. But how you do this depends on what method you used.

If you used HMRC's software

To amend a return that you filed using HMRC's online filing software, open the copy that you saved after submitting the original return.

You will see that the 'Introduction' page in the application now says 'Welcome back' and confirms the date and time you submitted your return. This page also shows the link, 'Amend your return'. Follow this link and you'll be presented with the return you submitted to HMRC and can make your amendment. There's on-screen help to guide you through the process. You can do this up to twelve times online using HMRC's software.

If you used commercial software

If you used commercial software to file your return, please check with your software provider if you're not sure how to amend it. If they don't offer an amendment feature, you can use the HMRC filing software. You'll need to download the software and then make your amendment for the same accounting period - but you'll have to enter all the data again in this form.

Time limits for amending return

All amendments, regardless of format, must be made within the time limit allowed.

Find information about amending your return and amendment time limits

Log in to Corporation Tax Online


Changing and managing your accounting period online

View the tax you owe and payments you have made online

You can view online how much Corporation Tax your company or organisation has paid, been repaid or still owes. You can also see a history of all Corporation Tax payments you've made or repayments made to you by HMRC.

How to view your Corporation Tax account - a demonstration

Log in to Corporation Tax Online

Change your company or organisation details

Limited companies

Limited companies can update the following details either through Corporation Tax Online or your Business Tax Dashboard:

  • contact or communication postal address (but not your company's registered name or office – you must change these at Companies House who will update their records and then automatically send the information to HMRC)
  • phone numbers - daytime, evening and mobile for your registered office and/or business, contact or communication address
  • email for your contact/communication address or registered office
  • fax number for your registered office and/or business, contact or communication address

Unincorporated organisation

Unincorporated organisations such as clubs or associations can update the following details either through Corporation Tax Online or the Business Tax Dashboard.:

  • organisation name
  • organisation address
  • contact or communication address
  • email for your contact or communication address
  • phone numbers - daytime, evening and mobile for your contact or communication address
  • fax number for your organisation's office and/or business or contact or communication address

Any online changes you make will normally be updated within 48 hours (this may take slightly longer over a weekend or bank holiday.)

See a demonstration of how to change your company details online

More information about changing your business details with HMRC

Log in to Corporation Tax Online

Add, change or remove your authorised accountant

If you've appointed a tax adviser or an accountant to act as your authorised agent to deal with HMRC on your behalf for Corporation Tax matters, they can let HMRC know about any changes using Corporation Tax Online. You can add, change or remove your authorised agent online.

Find out more about adding, changing or removing an authorised agent online

Company accounts: joint filing with Companies House and HMRC

Companies House and HMRC provide a joint filing service that allows most companies with relatively straightforward financial affairs to file their statutory accounts (as part of their Company Tax Return to HMRC) and send these (or an abbreviated version) to Companies House using a 'one stop' online facility.

Read more about the joint filing service


Other Corporation Tax Online features

HMRC has an Online Services Helpdesk answer any queries about Corporation Tax Online.

Contact the HMRC Online Services Helpdesk


More useful links

Register your company online with HMRC

Completing and filing your Company Tax Return

Help to file your Company Tax Return online

Find definitions of XBRL and iXBRL in the Corporation Tax glossary

HMRC Corporation Tax Online Service: answers to commonly asked questions

Corporation Tax Online: service issues

Corporation Tax Online: service availability