What Is iXBRL? Differences Between XBRL and iXBRL (UK Guide)
If you’re responsible for company accounts, tax filings, or regulatory submissions in the UK, you’ve almost certainly come across iXBRL. And if you’ve ever wondered what it actually is, why HMRC insists on it, or how it differs from XBRL, you’re not alone.
This guide explains everything in clear, practical terms.
You’ll learn:
- What XBRL and iXBRL mean
- How they work in practice
- Why iXBRL is mandatory in the UK
- How iXBRL fits into HMRC and Companies House filings
- How iXBRL files are created and submitted
What Is XBRL?
XBRL (eXtensible Business Reporting Language) is a global standard designed to make financial data easier for systems and regulators to read, analyse, and compare.
At its core, XBRL is built on XML, a technology that allows information to be structured and labelled so computers can understand what each number represents.
Why XML Matters
XML does not change your financial data. It adds meaning to it.
For example, instead of a system seeing a number, XBRL tells it what that number represents, such as revenue, expenses, or assets, reported under a specific accounting standard.
That context allows regulators and software to process large volumes of reports consistently and accurately.
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What XBRL Is Used For
XBRL is widely used for:
- Regulatory reporting
- Financial analysis
- Tax and statutory filings
- Comparing company performance across industries and regions
As a result, many regulators around the world have adopted XBRL for standardised financial reporting.
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What Is iXBRL (Inline XBRL)?
iXBRL (Inline XBRL) builds on XBRL by combining structured data and readable financial statements into a single document.
Instead of maintaining:
- One version for people to read, and
- Another version for systems to process
iXBRL merges both into one file.
What That Means in Practice
With iXBRL:
- Financial statements appear in a familiar format
- Files open in a standard web browser
- The XBRL tags are embedded behind the scenes
This allows people to read the accounts normally, while HMRC and Companies House extract and validate the tagged data automatically.
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XBRL vs iXBRL: What’s the Difference?
Both XBRL and iXBRL aim to standardise financial reporting, but they differ in how information is presented and consumed.
Area | XBRL | iXBRL |
Human-readable | No | Yes |
Machine-readable | Yes | Yes |
Special viewer required | Yes | No |
Designed for presentation | No | Yes |
Preferred for UK filings | No | Yes |
In simple terms, XBRL is designed primarily for systems, while iXBRL is designed for both people and systems. This is why regulators favour iXBRL.
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Why iXBRL Is Mandatory in the UK
The UK is currently the only jurisdiction where iXBRL filing is compulsory for corporation tax submissions.
HMRC and iXBRL
HMRC requires companies to submit:
- Statutory accounts
- Corporation tax computations
- Supporting financial information
These must be filed in iXBRL format when submitting a CT600 Company Tax Return.
This approach helps HMRC:
- Validate data automatically
- Identify inconsistencies more quickly
- Reduce manual review
- Improve overall compliance accuracy
Businesses and their agents can meet this requirement by:
- Using HMRC-approved software
- Preparing iXBRL files internally
- Engaging specialist iXBRL tagging services
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Companies House and Structured Reporting
Companies House has also adopted structured digital reporting and publishes XBRL and iXBRL accounts for public access. This reinforces iXBRL as a core component of the UK’s digital compliance framework.
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How Are iXBRL Files Created?
There are two main ways to produce iXBRL files.
Automated Generation
Specialist software converts source financial data into iXBRL by:
- Applying the correct taxonomy
- Tagging financial statements and notes
- Validating files against regulatory rules
This method is common in accounting and reporting systems.
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Utilizing the Potential of Outsourcing for Enhanced iXBRL Reporting
4 Reasons Outsourcing iXBRL Tagging is Ideal in 2024 & Beyond
Tagging Existing Accounts
Existing financial statements are:
- Converted into a structured format
- Tagged manually or semi-automatically
- Exported as compliant iXBRL files
This approach is often used when accounts are prepared outside automated systems.
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Why iXBRL Matters to Businesses
iXBRL is not just a regulatory requirement. It has real practical benefits.
For Regulators
iXBRL enables:
- Faster processing
- Higher data quality
- Consistent validation across submissions
For Companies and Accountants
iXBRL provides:
- A single submission-ready document
- Fewer filing rejections
- A clearer audit trail
- Reduced compliance risk
When implemented correctly, iXBRL simplifies the filing process rather than adding complexity.
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iXBRL, Taxonomies, and Validation Rules
Every iXBRL submission must comply with:
- The appropriate UK GAAP or IFRS taxonomy
- Financial Reporting Council (FRC) standards
- HMRC and Companies House validation rules
Using an incorrect or outdated taxonomy is one of the most common reasons for submission rejection, which makes taxonomy management critical.
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How DataTracks Helps
DataTracks supports organisations with iXBRL compliance by offering:
- Accurate iXBRL tagging
- Taxonomy-aligned reporting
- Pre-submission validation
- Support for HMRC and Companies House filings
Our focus is to ensure your reports are compliant, accurate, and ready for submission the first time.
To know how we can simplify your compliance reporting with our iXBRL Tagging Services, get in touch with a XBRL expert
