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Companies House Filing vs HMRC Filing with iXBRL 

Companies registered in the UK must file their accounts with Companies House, while all businesses (not just companies) must do the same with HMRC and their tax returns. Companies are therefore required to submit the same information to two different authorities. HMRC maintains a joint filing accounts template for small audit-exempt companies. When these companies fill up the accounts, data gets filed with both government departments electronically.


In 2006, Lord Carter’s report recommended that HMRC and the Companies House work together to provide a joint filing system. In 2011, HMRC mandated iXBRL filing for all business entities. Since then, both departments have worked closely to arrive at a single platform to accept iXBRL documents.

Below are some of

The key differences in XBRL filing with HMRC and Companies House:

i. Requirement:
While most UK business entities must file their accounts and tax computations in iXBRL format with HMRC, Companies House has not yet made it mandatory. It accepts voluntary filings.

ii. Format:
While HMRC accepts only the iXBRL format, Companies House currently accepts iXBRL and XBRL formats. This is likely to get changed and aligned with what HMRC accepts.

iii. Number of files:
While HMRC may require two files (Accounts + Computations) in iXBRL format, Companies House requires only one – Accounts alone.

iv. Taxonomies:
HMRC’s filings involve three taxonomies (a) UK-GAAP, (b) UK-IFRS and (c) UK-CT. Companies House filings involve three taxonomies (a) UK-GAAP-AE, (b) UK-GAAP and (c) UK-IFRS. UK-GAAP-AE (Audit Exempt) is just a subset of the main UK-GAAP. In rare cases, HMRC does accept accounts prepared using foreign taxonomies like US-GAAP.

v. XML file:
Even though iXBRL joint filing has the same tagged information going to both departments, they have different headers in their XML file.

vi. Validation:
HMRC validates and accepts all its filings through its gateway system. Companies House has its validation gateway for voluntary filers.

DataTracks UK is a leading provider of XBRL services to Accounting Firms and Businesses. DataTracks ( provides iXBRL Managed Tagging Services to help companies convert their financial statements and tax computations to iXBRL format for filing with HMRC. All DataTracks’ services are provided through an easy-to-use e-commerce portal. Users can register, create entities, place orders, pay, upload files and download iXBRL output when ready. DataTracks developed its XBRL conversion software in-house and was designed to support roll forward. As a result, clients are assured of consistency in tagging to their iXBRL documents and conforming to the latest taxonomy.

To find out more about DataTracks, visit or send an email to

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