HMRC iXBRL filing – corporation tax

Company Tax Returns must be filed online

HMRC (HM Revenue and Customs) is the department of the UK Government responsible for the collection of taxes.

Since 1 April 2011, for accounting periods ending on or after 1 April 2010, it is mandatory for companies to file their Company Tax Return with HMRC online using iXBRL.

Company Tax Return

A Company Tax Return comprises:

  • Accounts
  • Computations
  • CT600 form (including any supplementary pages)

 .... together with any other supporting documentation. In all cases where a Company Tax Return is filed online, the Accounts and Computations must be in iXBRL format.

Therefore if you have to prepare accounts under the Companies Act 2006, you must file your accounts and computations online in iXBRL format.

Filing your return – accounting periods ending on or before 31 December 2015

Existing HMRC PDF filing software

For accounting periods that end on or before 31 December 2015:

  • You can still file with HMRC's existing PDF filing software, which allows one to generate the CT600 and submit it together with uploaded iXBRL files for accounts and/or computations:
    • Note: HMRC is replacing its existing free filing PDF software with a new online service, designed for unrepresented companies and charities with straightforward tax affairs. The new online service is available now and you can use it if it suits your circumstances.  However you can still use the existing software until 1 April 2017 to download company tax returns for accounting periods ending on or before 31 December 2015, but not for later accounting periods. You should aim to file any outstanding returns for this period before the normal filing date, 31 December 2016. You will still be able to file any company tax returns downloaded prior to 1 April 2017, or file amendments to original returns already downloaded, until September 2017.
  • See Submitting iXBRL - the files you receive from us

Alternatively one can use commercial filing software to upload iXBRL files for accounts and/or computations.

For accounting periods that end after 31 December 2015, see below.

Submitting iXBRL - the files you receive from us

Uploading the iXBRL file(s)

As an alternative to completing the HMRC accounts template and/or the HMRC computations template, you instead attach your own accounts and computations to HMRC's online CT600 return form in iXBRL format (these iXBRL files can be supplied by our Tagging Service).

iXBRL file name has an HTML or HTM extension

The iXBRL file supplied by us has a .html or .htm extension  e.g. acme_acct_2015_01a.html   The uploading of the iXBRL file(s) takes place at the end of the process - see below for more details.

The fact that the iXBRL file has an .html or .htm extension means that you can click on the file and see a rough visual representation of the financial statement within a browser.  The file appears to be an ordinary HTML file, which can be a cause of confusion.  However rest assured that the iXBRL code itself is contained within the file (although it is not visible when viewed within a browser).

What about the PDF file you supplied?

The Tagging Report supplied as a PDF file to you is for your benefit only, so do not upload/supply this to HMRC.

HMRC validation - Will the iXBRL file that you supply be accepted by HMRC?

Yes it will.  All deliverables are fully checked and validation is performed before delivery to the customer - for UK customers your file is specifically tested with the HMRC validation service, so that you do not face any issues during filing.

Additional files forming part of the return

You can only include one iXBRL accounts file and one computation file as part of your online Company Tax Return. If iXBRL accounts are being included as part of the online return, any additional accounts forming part of the return must be attached as PDF files using the category 'other'.

Who can submit the iXBRL file to HMRC?

Only the registered taxpayer or the taxpayer’s authorised agent can file the accounts.  For example in the case of HMRC, this filing process is part of the CT600 submission.  The options here are either to utilize HMRC's Corporation Tax online filing service, or alternatively software with requisite CT600 submission functionality to automatically connect to HMRC's Corporation Tax online filing service.  In both cases the validated iXBRL file provided by us is attached before submission.

Help

Filing your HMRC return - the process in detail

The tax return

There are three components to the tax return:

  • Accounts - which can be submitted as a separate iXBRL accounts file
  • Computations - which can be submitted as a separate iXBRL computations file
  • CT600

Accounts - supplying iXBRL version of accounts to HMRC

At the start of Section 2 'Accounts':

  • 'Do you want to use the Accounts service?' - answer 'No', click the 'Next' button (and go directly to Section 3 'Computations')
  • You will later in Section 5 'Final review' be asked to attach your Accounts iXBRL file before completing the declaration at the end of the CT600 form
HMRC Company Tax and Accounts Return Service - Section 2 Accounts

Computations - supplying iXBRL version of computations to HMRC

At the start of Section 3 'Computations':

  • 'Do you want to use the Computations service?' - answer 'No', click the 'Next' button (and go directly to the Section 4 'CT600')
  • You will later in Section 5 'Final review' be asked to attach your Computations iXBRL file before completing the declaration at the end of the CT600 form
  • If you do not have a computations iXBRL file, answer 'Yes', and instead complete the relevant computations pages online within HMRC's service
HMRC Company Tax and Accounts Return Service - Section 3 Computations

Final Review - attaching the iXBRL files

In Section 5 ‘Final review’, this where you attach your iXBRL files:

  • Accounts – ‘You have selected not to use the Accounts part of this service.  Please attach your Accounts file in either inline XBRL (Extensible Business Reporting Language)’ ….
  • Computations – ‘You have selected not to use the Computations part of this service.  Please attach your Computations file in inline XBRL (Extensible Business Reporting Language)’ ….

HMRC Company Tax and Accounts Return Service - Section 5 Final Review

More information from HMRC

Filing your return – accounting periods ending after 31 December 2015

New HMRC CATO service

For accounting periods that end after 31 December 2015, if you wish to use HMRC's online service to file a tax return for your company, charity or association, one needs to utilise the new HMRC CATO service (Company Accounts and Tax Online - CATO):

Filing software

However, this new system no longer supports the uploading of iXBRL files for accounts and/or computations.  Instead one needs to use commercial filing software to achieve this:

  • If you are looking for a low-cost filing software solution, a possible supplier is Andica – the iXBRL accounts and/or computation files generated by our conversion service can be attached to the CT600 return and submitted online to HMRC using the Andica File by Internet feature –  more information ....

For accounting periods ending on or before 31 December 2015, see above.

Long period accounts and short period accounts

Long periods accounts help

The period that a company prepares accounts for (period of account) can be longer than 12 months.

However, the Corporation Tax period (accounting period or AP) cannot exceed 12 months.

Where the period of account does exceed 12 months, it must be split into more than one AP, with a separate set of tax computations and form CT600 for each.

The accounts should be attached for the first AP they cover, then none attached for the other APs covered.

The trading profits need to be apportioned between the APs. This may be done by time-apportionment, which is the most common method. However, a different method should be used if better information is reasonably available. Chargeable gains fall into the AP in which they arise instead of being time-apportioned.

If the company has prepared accounts for a period that is more than 12 months but less than 18 months, it must deliver a tax return within 12 months from the end of that period. If the period of account is more than 18 months, a tax return must be delivered within 30 months from the start of the period.

More information on accounting periods

FAQs (frequently Asked Questions)

Further information relating to the filing of company accounts and computations is detailed in our FAQs Overview - HMRC section