5 Step iXBRL Filing Process
Follow this systematic approach for successful iXBRL filing to HMRC and Companies House. Each step ensures compliance and accuracy.
Document Preparation
Gather and organize all required financial documents in digital format. Ensure accuracy and completeness before proceeding to tagging.
Required Documents:
- Statutory accounts (Balance Sheet, P&L, Notes)
- Corporation tax computation
- Directors' report and strategic report
- Auditor's report (if applicable)
- Company information (registration number, addresses)
Accepted Formats
Taxonomy Mapping & Tagging
Apply appropriate HMRC taxonomy tags to financial data elements. This is the most critical and technical step requiring understanding of UK GAAP and taxonomy structure.
Key Tagging Areas:
- Financial statement line items
- Monetary amounts and dates
- Contextual information (periods, segments)
- Calculation relationships
- Entity-specific disclosures
Common Challenges:
- Complex calculation linkbases
- Extension taxonomy creation
- Period-end date accuracy
- Decimal precision requirements
- Mandatory vs. optional tags
Validation & Quality Checks
Comprehensive validation ensures the iXBRL file meets all HMRC technical requirements and will be accepted by the filing gateway.
Schema Validation
- • XBRL syntax compliance
- • Taxonomy conformance
- • Instance document structure
- • XML namespace accuracy
Business Rules
- • Mathematical calculations
- • Mandatory field completion
- • Date logic validation
- • Cross-reference accuracy
Gateway Testing
- • Pre-submission checks
- • File size validation
- • Character encoding
- • Submission format tests
Regulatory Submission
Submit validated iXBRL files to the appropriate regulatory authorities through their online filing portals.
HMRC Submission:
- Corporation Tax Online portal
- Government Gateway authentication
- CT600 form + iXBRL computations
- Confirmation receipt provided
Deadline: 12 months after accounting period end
Companies House Submission:
- WebFiling portal (until April 2027)
- Approved software (from April 2027)
- iXBRL statutory accounts
- Payment of filing fee (£13-£40)
Deadline: 9 months after accounting period end