Finding Software to File Your Company Tax Return

All UK companies must file their Corporation Tax return online using commercial software. This software needs to format your accounts in a specific technical format called iXBRL, which HMRC systems can process automatically. Choosing the right software package will depend on your company's needs and whether you want to file both your tax return and annual accounts together.

Why you need commercial software

HMRC requires companies to file their Corporation Tax returns online using commercial software. You cannot simply log into a government portal and fill in forms directly like you can with Self Assessment.

You can only file a paper return if you have a reasonable excuse or are filing in Welsh. For the vast majority of companies, commercial software is the only option.

Understanding iXBRL format requirements

Most companies must format their accounts using something called Inline eXtensible Business Reporting Language (iXBRL). This is a technical format that allows HMRC's systems to read and process your accounts data automatically.

iXBRL files embed structured data tags within your accounts, so the information can be extracted and analysed electronically. While this sounds complex, the commercial software handles the technical formatting for you.

There are some exceptions to the iXBRL requirement. If your company falls into an exempt category, you can submit your accounts as a PDF attachment instead. However, most companies and organisations will need to use the iXBRL format.

What commercial software provides

Commercial software packages approved by HMRC provide several key functions:

• Preparation and formatting of your Corporation Tax return (form CT600)
• Production of accounts in iXBRL format
• Electronic filing directly to HMRC
• Production of tax computations in iXBRL format

Some software packages go further and allow you to file both your Corporation Tax return with HMRC and your annual accounts with Companies House at the same time. This can save time if you're managing both filing requirements together.

Finding approved software

HMRC maintains a list of commercial software suppliers whose products are approved for filing Company Tax Returns. Any software shown in HMRC's official list is accepted for filing purposes.

When choosing software, consider:

• Whether it produces both accounts and tax returns
• If it supports combined filing with Companies House
• The complexity of your company's accounts
• Whether you need tax computation features
• Cost and ongoing subscription fees
• Technical support availability

Many accounting software providers offer Corporation Tax filing as part of broader packages that include bookkeeping, VAT returns, and payroll features.

Taxonomy versions and technical specifications

HMRC uses different "taxonomies" for Corporation Tax returns. A taxonomy is essentially a standardised set of data tags that define how financial information should be structured and labelled in your iXBRL accounts.

These taxonomies are updated periodically to reflect changes in legislation and accounting standards. Your commercial software will need to use the appropriate taxonomy version for your accounting period.

The software provider handles which taxonomy version to use, but it's worth being aware that these technical standards exist and change over time. HMRC publishes guidance on when particular taxonomy versions should be used for different filing periods.

Filing annual accounts separately

While some software allows combined filing, you can also prepare your Company Tax Return and annual accounts separately. You might use one piece of software for Corporation Tax filing and a different system for your Companies House annual accounts.

If you're filing separately, you'll need to ensure both filings are completed within their respective deadlines. Companies House has its own filing requirements and deadlines for annual accounts, which differ from the Corporation Tax return deadline (typically 12 months after the end of your accounting period for Corporation Tax).

Getting started with software

Once you've selected a software package, you'll need:

• Your company's Unique Taxpayer Reference (UTR)
• Authentication credentials for HMRC online services
• Your company accounts and financial records
• Details of any tax adjustments and computations

Most software providers offer trial versions or demonstrations so you can check the system works for your needs before committing to a purchase.

If you use an accountant, they will have their own software and will handle the technical filing on your behalf. The software requirements are the same whether you file yourself or through an agent.

Sources

• Format for accounts forming part of an online Company Tax Return
• Filing your Company Tax Return online
• Company Tax Return taxonomies accepted by HMRC

This article provides general guidance based on current HMRC rules. For advice specific to your situation, speak to your accountant.