Register a software application at the Companies House developer portal and complete OAuth 2.0 authorization to obtain an access token scoped to the company and filing type you need to submit
Create a filing transaction by POSTing to the Transactions API endpoint (documented at developer-specs.company-information.service.gov.uk/manipulate-company-data-api-filing); the transaction ID returned is the container for all subsequent filing resources
Add the specific filing resource (e.g., a Registered Office Address change) to the transaction by POSTing to the appropriate resource endpoint using the transaction ID
Validate the filing payload against the API specification; the sandbox environment at https://api-sandbox.company-information.service.gov.uk is available for testing before submitting to production
Close and submit the transaction by PATCHing the transaction status to closed; Companies House processes the submission and returns a confirmation with the filing reference number
Poll the transaction status endpoint or check the Streaming API for the acceptance event confirming the filing has been registered
Known gotchas
Companies with 1,000 or more shareholders, complex share capital structures, or subsidiary undertaking disclosure requirements cannot use the API Filing service and must use alternative filing channels
The API Filing sandbox uses a separate identity/OAuth service at identity-sandbox.company-information.service.gov.uk — production OAuth tokens will not work against the sandbox and vice versa
Filing fees for confirmation statements differ between online submission (lower) and paper; always confirm current fee amounts at companieshouse.gov.uk before presenting them to users
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp