iXBRL Accounts: Software, Tagging & How to File UK Company Accounts

What are iXBRL accounts?

iXBRL accounts are statutory financial statements delivered in Inline XBRL format. They combine a human-readable HTML view with embedded machine-readable tags so that Companies House and HMRC can process them automatically. Every UK company that files online must submit its annual accounts in iXBRL.

In practice, an iXBRL accounts file looks like a normal web page showing the balance sheet, profit and loss, and notes — but each figure is wrapped in an XBRL tag linking it to the FRC taxonomy. That single file satisfies both the human-reading and machine-processing requirements of UK law.

What are iXBRL-tagged accounts?

iXBRL-tagged accounts are accounts in which every required monetary value, date, and text disclosure carries the correct XBRL tag. For example, turnover appears as core:TurnoverRevenue, fixed assets as core:FixedAssets, and the employee count as core:AverageNumberEmployeesDuringPeriod.

If a value is not tagged, or is tagged with the wrong element, the filing will either be rejected or processed incorrectly. That is why iXBRL tagging of accounts is the critical step in producing compliant iXBRL accounts.

How iXBRL accounts work

iXBRL accounts work by embedding tagging information inside a standards-compliant HTML document. When Companies House receives the file, its systems:

1. Parse the HTML for display on the public register
2. Extract the tagged values into structured data
3. Validate the data against taxonomy rules and arithmetic checks
4. Make the data available for statistical and regulatory purposes

The same file works for HMRC. When you file a CT600 Company Tax Return, the embedded iXBRL accounts are read directly by HMRC’s processing systems. If you want to understand the tagging side in more depth, read our complete iXBRL tagging guide.

What information is tagged?

The tagging scope depends on the size and reporting regime of the company. For a micro-entity using FRS 105, the tagged set is concise. For a small company using FRS 102 Section 1A, the set is larger. In general, tagged information covers:

• Entity identifiers: company name, registration number, accounting period dates
• Balance-sheet items: fixed assets, current assets, net current assets, total assets less current liabilities, creditors (split by maturity), net assets, equity
• Profit-and-loss items: turnover, profit or loss
• Approval metadata: director name, date of authorisation, approving body description
• Disclosure text: accounting standard applied, dormant status, etc.
• Employee count (where applicable)

How to create iXBRL accounts

There are three main routes to producing iXBRL accounts:

Route 1: iXBRL accounts software (recommended)

You enter your figures into purpose-built software that auto-tags against the FRC taxonomy and generates a compliant .xhtml file. This is the fastest and most reliable option for most directors and accountants. QuickXBRL follows this approach.

Route 2: Excel-to-iXBRL conversion

Some tools let you map an existing Excel workbook to taxonomy tags. You upload or paste your spreadsheet, confirm the mappings, and export iXBRL. This is useful when your accounts already live in Excel.

Route 3: Manual or scripted generation

Technically proficient users can generate iXBRL programmatically using XBRL libraries. This is flexible but requires ongoing maintenance to keep pace with taxonomy updates.

How iXBRL accounts are prepared for filing

Preparation is more than just tagging. A filing-ready iXBRL accounts file needs:

1. Correct taxonomy entry point for the accounting standard and period
2. Valid contexts for current year, prior year (if comparative), and any dimension axes used
3. Balanced arithmetic — balance-sheet totals, net assets equals equity
4. Complete mandatory tags — no missing balances, dates, or disclosures
5. Correct units — GBP for money, PURE for employee counts
6. Valid director approval — name, date, and approving body description tagged

iXBRL accounts and Companies House

Companies House accepts iXBRL accounts through its web filing service or via approved software filing. Key rules:

• Micro-entities may file a balance sheet only (with exemptions from directors’ report and P&L at Companies House) until April 2028
• From 1 April 2028, all companies must file via commercial software; web and paper filing close
• Late filing penalties apply (£150 upwards depending on how late)
• You can file iXBRL for both Companies House and HMRC in the same software session

The CATO free tagging tool was retired on 1 April 2026. For a full explanation of what changed and how to switch to premium software, read our CATO shutdown guide.

iXBRL accounts production software

iXBRL accounts production software handles the full lifecycle: data entry, tagging, validation, and submission. For small accounting practices, the right software reduces rework and keeps filings consistent across clients. If you need to prepare accounts from a PDF first, see our PDF to iXBRL guide. If your accounts are already in Excel, Excel to iXBRL conversion may be the fastest path.

What to look for in iXBRL accounts software

Beyond basic tagging, the best iXBRL accounts software includes:

• Auto-suggested tags based on your account layout
• Clear error messages that explain how to fix issues
• Support for comparative years and prior-period adjustments
• Export to PDF for human review before filing
• Audit trail and filing history
• Reasonable pricing for small practices and solo directors

Manual tagging vs automated/software-assisted workflows

Manual iXBRL tagging means writing or editing the HTML and XML directly. It is viable for learning but not for regular filing. Software-assisted workflows replace manual tag selection with auto-mapping, validation, and one-click filing.

For an accountant handling multiple clients, the difference is significant. A manual approach scales linearly with workload; software-assisted workflows stay fast regardless of volume.

iXBRL accounts example

Imagine a micro-entity with the following balance-sheet figures for the year ended 31 December 2025:

• Fixed assets: £45,000
• Current assets: £62,000
• Creditors within one year: £28,000
• Creditors after one year: £12,000
• Net assets: £67,000
• Share capital: £50,000
• Retained earnings: £17,000

In an iXBRL file, each of those numbers is wrapped in an ix:nonFraction element with the correct name attribute (e.g., core:FixedAssets), a context reference pointing to the right financial year, a unit reference of GBP, and a balance sign where required (creditors carry sign="-”). The result is a single HTML file that displays exactly like a paper balance sheet but can be parsed automatically by Companies House and HMRC.

Common errors when preparing iXBRL accounts

• Missing comparative year — if prior-year figures are shown on screen, they must be tagged too
• Broken arithmetic — net assets not equalling equity, or totals not adding up
• Wrong entry point — using last year’s taxonomy for this year’s accounts
• Untagged required text — the accounting-standard statement and approval line are mandatory
• Formatting errors — special characters in company names or addresses that break XML parsing
• Mixed regimes in one file — do not combine FRS 105 tags with IFRS tags

How to validate accounts before filing

Validation is the safety net between preparation and submission. A good validator checks:

• Schema validity against the chosen taxonomy
• Unit references are correct for each tagged value
• Arithmetic relationships hold (net assets = equity, balance-sheet totals)
• No duplicate or missing mandatory tags
• Context references are defined and consistent
• Dates are within the allowed accounting-period range

iXBRL tagging software like QuickXBRL runs validation continuously as you enter figures, so problems are caught before they reach the filing stage.

Software and workflow considerations for small accounting practices

A small practice has different priorities from a solo director:

• Volume — handling multiple clients efficiently
• Consistency — the same validation rules across all filings
• Audit trail — knowing when and by whom each filing was prepared
• Cost per filing — pricing that scales with usage rather than per-client licences
• Support — access to help when taxonomy questions arise

When evaluating best software for small accounting practice needs, look for volume pricing, multi-client dashboards, and a track record of keeping pace with FRC taxonomy updates.

How QuickXBRL simplifies iXBRL workflows

QuickXBRL is built around the micro-entity and small-company filing journey. It handles the technical parts of iXBRL accounts production so you can focus on the numbers:

• Auto-tagging against the current FRC taxonomy
• Real-time validation as you enter figures
• Direct filing to Companies House
• Support for FRS 105 micro-entity accounts and FRS 102 small-company accounts
• Affordable per-filing and practice-plan pricing

If you are a director preparing your own accounts or an accountant managing multiple clients, QuickXBRL removes the XML complexity without removing control.