What to File in iXBRL in the UK?
Complete guide to UK documents required in iXBRL format
UK companies must file Corporation Tax returns (CT600), tax computations, statutory accounts, and ESEF/UKSEF reports in iXBRL format. Comprehensive guide covering HMRC and Companies House filing requirements.
Quick Answer: What to File in iXBRL?
UK companies must file Corporation Tax returns (CT600), tax computations, and statutory accounts in iXBRL format. Listed companies also file ESEF/UKSEF annual reports.
- Corporation Tax (HMRC): CT600 forms and tax computations since April 2011
- Statutory Accounts: Annual financial statements to Companies House from 2027
- ESEF/UKSEF Reports: Listed company annual financial reports (FCA mandate)
- ESG Disclosures: Emerging sustainability reporting requirements
Need help with iXBRL filing? Get expert tagging from £50, 48-hour turnaround, zero-risk guarantee. View pricing
ISO
27001 Security Certified99.8%
Success First-Time Acceptance2,500+
Clients Trusted by UK FirmsHMRC
Approved Compliant ProviderCorporation Tax Returns (HMRC)
Since April 2011, HMRC requires all UK companies to file corporation tax returns and computations in iXBRL format. This mandate covers over 2.1 million companies annually.
The main corporation tax return form (CT600) must be filed in iXBRL format using the HMRC CT taxonomy. Includes company information, profit and loss account, and tax calculation.
Required Elements:
- Company identification and accounting period
- Profit and loss account summary
- Corporation tax calculation
- Tax reconciliation figures
- Close company declarations (if applicable)
Filed 12 months after accounting period end with corporation tax due
Detailed corporation tax computations showing adjustments to accounting profit to arrive at taxable profit. Must be tagged using specific HMRC computation taxonomy.
Computation Requirements:
- Accounting profit reconciliation
- Capital allowances calculations
- Trading adjustments and reliefs
- Losses brought forward and carried back
- Final taxable profit calculation
Uses HMRC Corporation Tax Computation taxonomy (CTComp)
Additional HMRC iXBRL Requirements
VAT returns must be submitted digitally through compatible software. Corporation Tax MTD planned for companies above £10m threshold from April 2026.
Multinational groups with consolidated revenue above €750m must file CbC reports in XML format to HMRC for tax transparency.
Financial institutions must file FATCA and Common Reporting Standard returns in XML format for international tax compliance.
Statutory Accounts: April 2027 Software Mandate
From April 1, 2027, all UK companies must file statutory accounts using approved commercial software in iXBRL format under the Economic Crime and Corporate Transparency Act 2023.
- Paper and web filing through Companies House website eliminated
- Affects all 2.1+ million active UK companies and LLPs
- Full iXBRL tagging becomes universal requirement
Filing deadline: 9 months after accounting period end | Applies to periods beginning on or after April 1, 2027
Simplified accounts for micro entities meeting two of three criteria: turnover ≤£632k, balance sheet ≤£316k, employees ≤10.
- Balance sheet (simplified format)
- Profit and loss account (optional)
- Notes to the accounts (minimal)
- Directors' report (if required)
Uses FRC Taxonomy for Micro Entities (FRS 105)
Standard accounts for small companies meeting two of three: turnover ≤£10.2m, balance sheet ≤£5.1m, employees ≤50. Full primary statements with reduced note disclosures.
- Balance sheet (full format)
- Profit and loss account
- Notes to the accounts (reduced)
- Directors' report
- Auditor's report (if applicable)
Must use FRS 102 or FRS 105 accounting standards
Comprehensive accounts with full disclosure requirements. Medium companies exceed small thresholds but not large. Large companies exceed medium criteria.
- Complete primary financial statements
- Comprehensive notes to accounts
- Strategic report (large companies)
- Directors' report with additional content
- Mandatory audit and auditor's report
Large companies must include strategic report
Charitable companies must follow standard company law requirements plus additional charity-specific disclosures under FRS 102 and Charities SORP (FRS 102).
- Statement of Financial Activities (SOFA)
- Restricted and unrestricted funds analysis
- Trustees' annual report
- Public benefit statement
- Charity-specific note disclosures
Dual filing to Companies House and Charity Commission
April 2027 Software Mandate
The Economic Crime and Corporate Transparency Act 2023 requires all UK companies to use approved commercial software for statutory accounts filing from April 1, 2027.
What Changes:
- Paper filing completely eliminated
- Web filing through Companies House website ends
- All companies must use commercial software
- Full iXBRL tagging becomes universal requirement
Who Is Affected:
- All active UK companies (2.1+ million)
- Micro entities and dormant companies included
- Limited liability partnerships (LLPs)
- Companies currently using paper or web filing
April 2027 Software Mandate Details
The Economic Crime and Corporate Transparency Act 2023 requires all UK companies to use approved commercial software for statutory accounts filing from April 1, 2027.
What Changes:
- Paper filing completely eliminated
- Web filing through Companies House website ends
- All companies must use commercial software
- Full iXBRL tagging becomes universal requirement
Who Is Affected:
- All active UK companies (2.1+ million)
- Micro entities and dormant companies included
- Limited liability partnerships (LLPs)
- Companies currently using paper or web filing
Listed Company Reports (FCA)
The Financial Conduct Authority requires listed companies to file annual financial reports in ESEF/UKSEF format with comprehensive iXBRL tagging of IFRS consolidated financial statements.
Listed companies must prepare annual financial reports in XHTML format with iXBRL tagged IFRS consolidated financial statements using the ESEF/UKSEF taxonomy.
UKSEF Components:
- XHTML annual financial report
- iXBRL tagged IFRS primary statements
- Note disclosure tagging (block level)
- Entity-specific extensions when needed
- Digital signature and filing metadata
Premium Listed: 2022 onwards | Standard Listed: January 2026
Environmental, Social, and Governance (ESG) reporting is transitioning to structured digital formats. UK regulators are developing taxonomy extensions for ESG disclosures aligned with international standards.
ESG Reporting Elements:
- Climate-related financial disclosures (TCFD)
- Sustainability metrics and targets
- Environmental impact measurements
- Social responsibility indicators
- Governance structure and policies
Mandatory structured ESG reporting expected 2026-2027
Emerging International Requirements
ISSB Standards
International Sustainability Standards Board (ISSB) S1 and S2 standards for general sustainability and climate-related disclosures in digital formats.
Global Minimum Tax
Pillar Two global minimum tax reporting for multinational groups with consolidated revenue above €750m in structured XML format.
EU CSRD Alignment
Corporate Sustainability Reporting Directive (CSRD) alignment for UK subsidiaries of EU companies requiring digital sustainability reporting.