Preparing for 2026 iXBRL Mandates: A Practical Checklist

With regulators moving to broader software-based filing obligations, firms must be methodical in their readiness work. This checklist prioritises actions that protect filing accuracy, minimise disruption, and make the transition manageable.

Quick Checklist: 8 Essential Tasks

1. Inventory & Classification: Catalogue entity types, filing frequencies, and existing report formats across clients.
2. Technical Mapping: Map your chart of accounts to FRC taxonomy elements and create a canonical mapping document.
3. Validation Pipeline: Build a repeatable validation flow: taxonomy validation, XBRL validation, and procedural sign-offs.
4. Data & Tooling: Ensure your source data exports are structured and that iXBRL software supports your workflows (APIs, templates, rollback).
5. Training & Roles: Assign clear roles for tagging, review, and final sign-off; provide practical training and playbooks.
6. Test Submissions: Run end-to-end dry-runs to Companies House/HMRC testbeds where possible and iterate on errors.
7. Security & Retention: Verify secure transport, encryption, and record retention meets regulatory expectations.
8. Client Communication: Set expectations, timelines and any client-side data requirements early in your onboarding process.

Technical Tips

Prioritise automated mapping with manual overrides and store canonical mappings in version control. Use validation logs and compare tag sets between runs to detect regressions early.

Process & People

Define simple, auditable sign-off steps. Give senior reviewers a tight checklist and a short turnaround for exception resolution; automation should handle the repetitive work.

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