The Companies House public data API is free, well-documented and exposes most of what a UK accounting firm needs to know about a limited company: incorporation details, registered office, directors, PSCs, filing history and charges. The question is not really "should we use the data" - every modern firm does - but "should we call the official API ourselves, or pay a commercial wrapper to do it for us?" The right answer depends on how many lookups the firm runs, what it wants to do with them, and how much engineering time it is willing to invest.
What the official API gives you
The official Companies House API is two products in practice: the public data API (REST, JSON, free, rate-limited at 600 requests per 5 minutes per key) and the streaming API (real-time changefeed of filings and company events). Together they cover company search, company profile, officers, persons with significant control, filing history, registered office address and document images. The streaming API is the one that lets a firm move from "we look it up when we need it" to "we know within seconds when one of our 400 clients files anything". Both require a Companies House developer account and an API key.
What direct integration actually costs you
Calling the API directly is technically straightforward but operationally non-trivial. You need: a place to store the API key safely; a polite caller that respects rate limits and backs off correctly; a cache so you are not re-fetching the same company profile twenty times a day; a normaliser that maps Companies House field names to whatever you call them internally; and a retry-and-alert layer for the inevitable Companies House outage. None of this is hard for a competent developer, but it is half a week of work plus ongoing maintenance, and it is not the kind of work most accountancy firms employ engineers to do.
What commercial wrappers add
Commercial Companies House wrappers (Inform Direct, FirstOrderIT, Validis-style enrichment services, and the Companies House features built into practice management products) sit on top of the official API and add: enriched data (group structures, beneficial ownership maps, sometimes credit data); polished UIs; bulk-monitoring of large client portfolios; alerting; and document filing capability. Filing capability is the genuinely different bit - submitting CS01, AP01, TM01 and similar forms is not part of the public API. That requires the separate transactional service, which has stricter onboarding and is what most filing wrappers monetise.
The honest cost comparison
Direct integration: one-off engineering cost (rough order £3,000 to £8,000), then near-zero marginal cost. The API itself is free. Commercial wrappers: typically £10 to £40 per filing submitted, plus a monthly subscription on the order of £30 to £150 for read access and monitoring. For a firm with 200 active limited companies, the wrapper approach costs in the low thousands per year. For a firm of 2,000, it costs five-figure sums per year. There is a crossover point where building beats buying, but it sits higher than most firms realise.
Read vs write - the bit nobody explains clearly
Most firms only need read access: pull the data, populate the client record, monitor the deadlines, alert when something changes. Read access via the public API is free and uncomplicated. Write access (filing the actual CS01 or AP01) is a different product entirely, requires presenter credentials, has fees per submission, and is where commercial wrappers genuinely earn their keep. Many firms run a hybrid model: direct read for monitoring and enrichment, commercial filing via Inform Direct or similar for the submissions themselves.
Where Accupe sits in this picture
Accupe reads from the Companies House API natively to auto-populate UK company records and to monitor filing deadlines as part of the Compliance Radar. The integration is one of the read-side use cases - it gives the firm a unified view of every client's next confirmation statement, next accounts filing and next event without anyone polling the gov.uk website manually. Accupe does not submit filings to Companies House; for the actual submission the firm uses its filing tool of choice (Inform Direct, Xero Tax, TaxCalc, the Companies House web filing service). The line is deliberate: Accupe is the visibility and workflow layer, the filing tool does the filing.
Streaming, monitoring and the "we got blindsided" risk
One of the better arguments for going beyond ad-hoc lookups is that Companies House changes - director appointments, address changes, charges, mortgages, gazette notices - happen between your client meetings. A firm that learns about a director's resignation a week after it filed because a client casually mentions it has a problem. Whether you build a streaming consumer yourself or pay a wrapper to do it, set up monitoring. The Compliance Radar in a practice tool is the consumer of that data, not the producer.
How to choose without overcomplicating it
Under 100 client companies and limited engineering resource: use whatever practice or filing tool you already pay for, do not build. 100 to 500 client companies, some appetite for tooling: hybrid model - practice tool for read and monitoring, commercial filing tool for submissions. 500+ client companies and a real product or data team: building a direct integration starts to make sense, primarily for the enrichment and analytics use cases that wrappers do not cover.
Closing
The Companies House API is a quiet superpower for UK accountancy firms. Most firms underuse it not because the data is expensive but because nobody on the team is paid to think about it. Pick the access model that suits your scale, make sure monitoring is automated, and stop relying on someone remembering to check.