Corporation Tax Online: setting up and managing your online account

This guide will help you find out what you need to do to set up (register and enrol) for the HM Revenue & Customs (HMRC) Corporation Tax Online Service or add the service to your existing online account.

You can also find out about the features of the Corporation Tax online service, such as submitting and amending your Company Tax Return, viewing your payment history, changing your company details, or appointing a tax agent or adviser.

You must sign up for Corporation Tax Online whether you are planning to use HMRC's free software or commercially available software to submit your Company Tax Return.

On this page:

Corporation Tax Online - an overview

HMRC's Corporation Tax online service is safe, secure and reliable. The following features allow you to carry out many tasks online. It's designed to work with either a broadband or standard dial- up internet connection so you don't need the latest high-tech computer.

Please note if you've used HMRC's online registration service to register your limited company for Corporation Tax you are automatically enrolled for the Corporation Tax online service.

You can use the Corporation Tax online service to:

  • submit your Company Tax Return to HMRC over the internet using HMRC's free online filing software or commercially available software
  • submit 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

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Setting up the Corporation Tax online service

Before you get started

Before you can submit your Company Tax Return online and/or use the other features of the online service, you need to sign up for Corporation Tax Online. You need to have your company or organisation's Corporation Tax reference handy along with either of the following:

  • Companies House registration number (CRN)
  • the postcode of your registered office or if you don't have a registered office, the postcode of your main business address

Please note: if you use or plan to use a tax agent or adviser to submit your Company Tax Return, then your agent must be set up to use Corporation Tax Online. But if you want to use any other features of Corporation Tax online service - for example to view your company's payments and liabilities - then you need to set up an online account too.

If you are already set up for other HMRC Online Services

If you're already set up as a company or unincorporated organisation (both known to HMRC as an '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 you must:

  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

If you are new to HMRC Online Services

If you're a new user and you're not already set up for another HMRC Online Service, and you did not use HMRC's online registration service to register your limited company for Corporation Tax, you'll need to set up ('register' for) an HMRC online account. You then sign up ('enrol') for Corporation Tax Online. The following is an overview of the registration and enrolment process:

  1. Go to the HMRC homepage and select 'Register (new users)' in the 'Do it online' section.
  2. Follow the link to 'Sign up for HMRC Online Services' in the 'When to sign up for HMRC Online Services separately' section.
  3. Click on 'Organisation', and select 'Corporation Tax (CT)' on the next page.
  4. Read and accept the terms and conditions of HMRC Online Services.
  5. Enter your company's name and email address.
  6. Create a password and keep this safe as you'll need it to use the online service.
  7. Take a note of your User ID which will appear on screen - you'll need it to use the service.
  8. Enter information about your company or organisation - see the 'Before you get started' section above. On-screen instructions will guide you through the enrolment process.

Signing up for Corporation Tax Online - a beginner's guide (PDF 240K)

Log in and enrol for Corporation Tax Online

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Activating the Corporation Tax online service

When you've used HMRC's online registration service to register your business for Corporation Tax, set up your Corporation Tax Online account, or added it as another service, HMRC will send you an activation code (also known as an Activation PIN) through the post. This code can take up to seven days from when your registration is verified to arrive so don't leave it until the last minute to register.

To activate the Corporation Tax online service you must log in to your online account and enter this code when asked. You won't be able to submit your return or use any other aspects of the online service until you've activated the service.

Log in and activate the Corporation Tax online service

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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 a HMRC Corporation Tax online account before you can file returns online.

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

  • Register 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.
    • Register and enrol one of the group within 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

Group Payment Arrangements for Corporation Tax

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Submitting your Company Tax Return online

From 1 April 2011, you must submit your Company Tax Return online for accounting periods ending after 31 March 2010. Additionally, your tax computations and, with very few exceptions, the accounts that form part of your Company Tax Return, must be submitted in Inline eXtensible Business Reporting Language (iXBRL) format.

You can submit your return online using HMRC's free online filing software, commercially available software, or software you've developed specially to meet your company's needs. Commercial software may offer greater flexibility for most companies.

More about switching from paper to online returns and paying electronically

Using HMRC's free software

HMRC's online filing software - which is a downloadable PDF - is aimed at smaller companies and organisations with less complex 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 submit:

  • 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 submit 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 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.

Follow the links below to find more information about who can use HMRC's software and a beginner's guide to using it to submit 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 that applies from 1 April 2011.

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

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Amending a Company Tax Return you've already filed

You can easily and securely amend a return you've already submitted to HMRC.

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.

You can also make your amendment on paper and send it to your Corporation Tax Office.

Find your Corporation Tax Office

If you used HMRC's software

To amend a return that you filed using HMRC's online filing software, open the file 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'. Select 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.

If you filed a paper return

Even if you filed a paper return you can also amend it online using HMRC's online filing software.

You must sign up for Corporation Tax online service first. Then you need to download the software and make your amendment for the same accounting period. You'll have to enter all the data again in this form.

Time limits for amending returns

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

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Changing and managing your accounting period online

Changing an accounting period

You can use HMRC's online filing software or commercial software to submit a return even if your Corporation Tax accounting period has changed. This means your return can cover:

  • your 'normal' Corporation Tax accounting period
  • a different accounting period to your normal one
  • a completely new accounting period if your company or organisation has started in business or become active after a period of dormancy

If you use HMRC's online filing software, you can change the accounting period that's shown, or tell HMRC about a new one by following the 'File a return and accounts' on-screen prompts. You can then download and complete the HMRC online filing software for the changed accounting period.

If you use commercial software, you can provide the accounting period start and end dates as part of the return and depending on your software package, the software may enter this for you automatically.

Whether you use either HMRC's online filing software or commercial software, HMRC will update their records to reflect the change of accounting period on submission of your return. But whichever software you use, your accounting period can't be more than 12 months long (although it may be shorter depending on your company or organisation's circumstances).

What to do if a period of account is longer than an accounting period

A Corporation Tax accounting period can't be longer than 12 months. For example, if your company accounts are drawn up for an 18-month period (its 'period of account'), and your company is trading throughout, you must submit two Company Tax Returns because you'll have two Corporation Tax accounting periods. The first accounting period covers the first 12 months and the second period covers the remaining six months.

Read more about Corporation Tax accounting periods

When submitting your returns online, you need to file a separate CT600 return form for each accounting period, but you only need to include your company accounts - in iXBRL format - with one of the forms.

If you're using HMRC's online software, it will show you the accounting periods based on information held by HMRC, but you may need to amend them. You do this using the 'Change Accounting Period' function (see previous section). You can then select and download the online return form for each accounting period.

For the first accounting period you only need to complete:

  • the accounts template for the whole period of the accounts
  • the computations for the first accounting period

For the second accounting period:

  • You don't need to attach the accounts again. Instead, select 'No' to the question 'do you want to use the accounts service?'
  • Complete the computations template for the second accounting period.
  • In the 'Final Review' section select 'The period that the accounts are drawn up for differs from the accounting period. The accounts have been or will be sent with a separate CT600 return.' to confirm why you haven't included accounts.

If you're using commercial software, you can follow the same approach as above.

Alternatively, for the first accounting period you can attach:

  • the accounts for a period longer than the first accounting period
  • separate computations for both accounting periods

For the second accounting period, you'll need to explain that the accounts and computations were attached to the return for the first accounting period:

  • Select the reason for no accounts as 'The period that the accounts are drawn for up differs from accounting period. The accounts have been or will be sent with a separate CT600 return.'
  • Then select the reason for no computations as 'The period that the computations are drawn up differs from accounting period. The computations have been or will be sent with a separate CT600 return.'

Instead of the options above, you could attach the accounts and both computations in your returns for the first and second accounting periods.

Please contact your software provider for advice if you need more information about how to use your software.

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

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Other Corporation Tax Online features

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.

You can also choose to create a Business Tax Dashboard to view the balance of your Corporation Tax and VAT and PAYE accounts on a single page. This is a 'view only' service and the dashboard does not enable you to reallocate any payments between the different taxes.

Before you can set up a dashboard for the online services you have signed up for, you must activate your Corporation Tax online service.

As you can only view details for one company on your dashboard, this service is not suitable for groups of companies (see the section above on 'groups').

How to view your Corporation Tax account - a demonstration

Log in to Corporation Tax Online

Read more about setting up a Business Tax Dashboard

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 - these changes must be notified to Companies House who will update their records and then automatically send the information to HMRC)
  • phone numbers - (daytime, evening, 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.

Organisations

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

  • organisation name
  • organisation's address
  • contact or communication address
  • email for your contact or communication address
  • phone numbers - daytime, evening, 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, you 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 submit 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

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Corporation Tax Online: finding detailed guidance

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 to find links to:

  • the underlying directions and legislation to require companies to file online and pay electronically
  • help on who needs to submit accounts in iXBRL or PDF format
  • guidance on when, how and what data to tag in iXBRL format
  • guidance on how HMRC will manage the transition to online filing

Corporation Tax - detailed guidance on online filing and electronic payment

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Paying Corporation Tax electronically

From 1 April 2011, as well as filing your Company Tax Return online, you must also pay your Corporation Tax and related payments, for any accounting period, electronically. Related payments include interest charged on overdue Corporation Tax and penalties for not filing your Company Tax Return on time.

There are many ways you can pay Corporation Tax electronically. Find out more by following the link below.

How to pay Corporation Tax

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Online Services Helpdesk

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

Contact the HMRC Online Services Helpdesk

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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

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