Companies House data can help an accountancy practice define, find and review potential clients, but it cannot tell you which of them want or need an accountant.
Each field on the register describes an entry in a legal record, not a business decision. Incorporation is not trading, an "active" status is not evidence of current activity, a registered office is not necessarily a trading address, and a Standard Industrial Classification (SIC) code is a self-reported label rather than a verified one. The right way to search the register — a single website search, the search API, a downloadable snapshot, or a repeatable spreadsheet routine built on any of these — depends on the volume you need, how often you repeat the search, how finely you filter it, whether you need an export, and how much manual review follows.
What the public register actually shows
Companies House is the registrar of companies for England, Wales, Scotland and Northern Ireland. The register mixes three kinds of information, and it matters which you are reading:
- Filed data — submitted by the company or its agent in an application or statutory filing: company name, registered office, SIC codes, officer appointments, confirmation-statement content.
- Derived data — worked out or maintained by Companies House from those filings and its own administrative action: company status, status detail, and accounts or confirmation-statement due dates.
- Third-party-presented data — the same facts, repackaged by a search tool, data reseller or CRM enrichment vendor, adding its own delay or transcription error on top of the source.
Companies House's own guidance on searching the register describes results as "an extract from the register … updated on a regular basis", notes that "a close review of each document during registration is not always possible", and states that "Companies House cannot take any responsibility for the consequences of errors or omissions" (GOV.UK, checked 17 September 2026). Register data can be reused, including commercially, under the Open Government Licence v3.0.
Scale matters too: 192,287 incorporations were recorded across the UK in April to June 2026, and 5,516,377 companies sat on the register at the end of that quarter (Companies House official statistics, checked 17 September 2026). That differs from an Office for National Statistics "business birth" — a business registering for VAT or PAYE, not incorporating — which ONS put at around 317,000 across the UK in 2024 (ONS business demography, checked 17 September 2026). The two counts answer different questions and should not be quoted as one figure.
For that national flow broken down by local authority and industry, with the calculation method published alongside it, see the company registration statistics and their methodology.
Ten fields, mapped to their cautious use and limits
The table below reads each part of a company record against what it supports and what it does not, drawing on current Companies House and GOV.UK guidance cited beside each caveat.
| Field | Source and filing context | Freshness and missingness caveat | Cautious practice use | What it cannot establish | Review action |
|---|---|---|---|---|---|
| Company name | Filed at incorporation and on any later change-of-name filing. | Usually current, but a company can trade under a name that never appears on the register. | Identify a specific entity and match results back to it. | The name someone actually trades under. | Check previous names (below) and the company's own site before assuming a mismatch means no match. |
| Company number | Assigned once, permanently, at incorporation. | Never changes; always present. | The one safe key for de-duplicating and joining records pulled at different times. | Nothing about the company — it identifies, it does not describe. | Dedupe and cross-reference on this field, never on name, which sources format differently. |
| Incorporation date | Fixed at registration. | The register updates continuously, so a very recent incorporation may still be processing. | Bound a "recently incorporated" search window. | When, or whether, the company started trading — HMRC treats being active for Corporation Tax as separate from incorporation (GOV.UK, checked 17 September 2026). | Treat the date as registration age, not trading age. |
| Company status | Derived by Companies House from filings and its own action; values include active, dissolved, liquidation, receivership and administration, with a status detail such as active-proposal-to-strike-off. | Status lags the event behind it — a strike-off proposal or insolvency step is visible only once processed. | Screen out companies that are dissolved, in liquidation or otherwise no longer live. | "Active" means live on the register, not trading, staffed or operating. | Re-check status close to the point of contact; it can change after your search. |
| Company type / subtype | Filed at incorporation (private limited company, LLP, PLC and others); some subtypes, such as a community interest company, are filed as an addition to the base type. | Stable once set, though a company can convert between types. | Narrow a search to the legal forms a practice can serve. | Size, sector or turnover — type says nothing about scale. | Pair type with SIC codes and filing history rather than treating it alone as a qualifier. |
| Registered office address | Filed by the company, subject to the "appropriate address" rules that took effect on 4 March 2024 (GOV.UK, checked 17 September 2026). | Free text, with no verified geocoding; it can be updated at any time. | A text match on part of the address, not a geographic boundary. | Where the company trades or is staffed — the address may belong to an accountant, solicitor or formation agent acting for it. | Watch for many results sharing one address before treating each as a separate business; see registered office versus trading address. |
| SIC codes | Self-reported, up to four codes from the Companies House condensed list. | Only updated via a confirmation statement; a dormant or non-trading code left on an active company is a common discrepancy (Companies House blog, checked 17 September 2026). | Filter by stated sector; treat a company holding more than one relevant code as one company, not several. | Current trading activity or buying intent — a classification, not a verified activity. | Flag or exclude codes 99999 (dormant) and 74990 (non-trading); see SIC codes explained. |
| Officers | Filed on appointment; a director's service address is public. | Appointments and resignations are filed as they happen, with the usual processing lag. | Confirm a formal appointment before addressing correspondence to a named individual. | That the person is the right contact for professional services, or reachable there. | A director's name is personal data even on a public register — treat it with that care in outreach. |
| Accounts and confirmation-statement due dates | Calculated from the company's accounting reference date and filing history. | A date can show as approaching or overdue before a filing is processed. | A weak proxy for administrative activity, not a business signal. | Financial health, size or trading — only that a deadline exists or was met. | Do not treat one date alone as decisive; read it alongside current status. |
| Previous names | Filed on any change of name. | Present only where a change happened; absence is not proof the company never traded under another name informally. | Reconcile a company known by an earlier name, or spot a recent rebrand. | The reason for a rename or continuity of the underlying business. | Check this field before assuming two similarly named entities are, or are not, related. |
A hypothetical practice, traced through the fields
This example is hypothetical: it uses no real company names or records, and the counts below are aggregate totals only.
Take a four-person accountancy practice in Bristol that wants owner-managed trades and small construction contractors as clients, reviewing around 15 companies a week. It could search using several fields above together: company type (private limited company), status (active), incorporation date (a rolling 31-day window — 18 August to 17 September 2026 when tested), registered office (containing "Bristol"), and SIC code.
A specialist search — Bristol, incorporated in the last 31 days, SIC 43220 (plumbing, heat and air-conditioning installation) — returned 8 results when tested on 17 September 2026. A broader search combining three related trade codes (43210 electrical installation, 43220, and 43390 other building completion and finishing) returned 5, 8 and 7 results across three separate one-code searches — 20 in total, though a company holding two of those codes would be counted twice, since each search is read separately. Widening further, to any registered office containing "Bristol" with no SIC filter at all, returned 546 results in the same window — an upper bound on how large an unfiltered "construction trades in Bristol" search could get.
None of these counts says which companies want or need an accountant, whether they have started trading, or whether their registered office is where the work happens — the caveats above still apply. What the trace shows is how bounding a search turns a register of millions into a number one practice can actually review.
Four ways to run the same search, compared
On 17 September 2026, one defined task was run and compared across four routes, in a clean browser session with no account: list active private limited companies incorporated in the last 31 days whose registered office contains "Bristol" and whose SIC code is 43220 — the specialist search above, which returned 8 results.
| Criterion | Web Advanced company search | Advanced search API | Free Company Data Product snapshot | Weekly spreadsheet workflow on the web CSV |
|---|---|---|---|---|
| Availability and setup | No account; usable straight away at the Advanced company search page. | Free API key registration via the advanced search API; needs someone able to call an endpoint or write a script. | No account; download the roughly 469 MB zip (or seven 48–70 MB parts) from the Free Company Data Product page. | No account; only a spreadsheet to hold the running list. |
| Filters supported | One SIC code per search — a comma-separated list returns "Error: Enter a valid SIC code"; address is free-text; incorporation-date range; status and type checkboxes. | sic_codes takes a comma-delimited list or repeated values, so several codes run in one call, plus the same address, date, status and type parameters. | No live filter — filter afterwards across four SIC-text columns (SICCode.SicText_1–4) and one address column; no built-in date range. | Same filters as the web search, from the same download. |
| Repeatability and rerun effort | Fully manual — re-enter the filters and click Search each time; nothing is saved. | Once written, a script reruns unattended and can be scheduled, but someone must build and maintain it. | Downloading a new multi-hundred-megabyte file and re-filtering it, every month. | A manual repeat of the web search and download, then an append-and-dedupe step — minutes a week, no code. |
| Export | A "Download results" CSV button, 11 columns, capped at the first 5,000 rows. | Returns JSON; a CSV is something the caller has to build. | The snapshot file is the export; a filtered subset must be saved out separately. | The same web CSV, appended into a running file the practice keeps. |
| Coverage and limits | Display capped at 10,000; download capped at 5,000. | size accepts 1 to 5,000 per call, paged with start_index; rate-limited to 600 requests per five minutes. | Live companies only, as one full-register file. | Same 10,000/5,000 limits as the web search, applied each week. |
| Freshness | Reflects the register as updated, subject to normal processing time. | The same live register as the web search. | "Compiled up to the end of the previous month and made available for download within 5 working days" (GOV.UK, checked 17 September 2026) — this month's incorporations wait for next month's release. | Same live freshness as the web search, refreshed on whatever cadence you rerun it. |
| Cost | Free. | Free to register. | Free. | Free. |
| Main caveat | Nothing is remembered between sessions, so a forgotten filter is easy to miss. | Needs setup and maintenance most small practices will not have in-house. | Freshness lag makes it unsuitable for a "last 31 days" task, and it is a large file for a narrow one. | Only as accurate as the manual dedupe step — a rerun with a changed filter will double-count. |
For this exact task, the manual route on its own was entirely sufficient: eight results is a number one person can read directly off the results page, without downloading anything or building a workflow around it. The case for something more repeatable grows with the number of profiles you run, how often you rerun them, and how much you need results kept and deduplicated between weeks — not with a single search of this size.
Running the search yourself
These steps reproduce the search above and were followed exactly on 17 September 2026:
- Open the Advanced company search page — no sign-in required.
- Click "Show all filters" — sections are collapsed by default.
- Enter a full or partial registered office address.
- Enter the incorporation date From and To (day, month, year).
- Tick a company status (for example, Active).
- Enter one SIC code.
- Tick a company type (for example, Private limited company).
- Click "Search" and read the "N results" count; results list 20 at a time.
- Click "Download results" for a CSV, if needed — only the first 5,000 rows come down.
Completion check: a results count, or a downloaded CSV, that matches the filters you actually set, saved or noted with the date. Note the exact filter values if you plan to repeat the search, since none are saved by the site itself. A fuller walkthrough with screenshots is in finding newly incorporated companies on Companies House; turning a shortlist into a standing profile is covered in building a new-company search profile.
Where these fields and filters can mislead
Four failure patterns show up often enough to check for deliberately:
- Stale or ambiguous fields. A status, SIC code or address can be technically current while no longer describing the company well — see the freshness caveats in the field table above before treating any single field as decisive.
- Multiple SIC codes, counted more than once. Because the web search accepts one SIC code at a time, running several searches for related codes can count the same company under each one it holds, as the hypothetical example above shows. See SIC codes explained for how to treat a company with more than one relevant code.
- Registered-office concentration at provider addresses. A search can return several results sharing one registered office — often an accountant's, solicitor's or formation agent's address rather than each company's own — inflating the apparent number of distinct, separately reachable businesses. See registered office versus trading address.
- Text-match false positives. The address filter matches text, not geography: "Bristol" matches any address containing that word wherever it sits, and misses a genuine Bristol address that omits the word, such as one given only by postcode. Read each result rather than trusting the filter to have done the geographic work for you.
Once you have a shortlist
Everything above stops at a list of companies matching a defined search. Reviewing each one, deciding whether it is relevant, and following up in a way that respects PECR and UK GDPR is a separate question — see the guide to finding, reviewing and contacting new companies.
How Launch Register can help
The repeated step above — rerunning a filtered search, downloading the results and deduplicating them against last week's list — is the one a subscription service can take over. Deciding whether each match is relevant, and whether to make contact, stays with the practice. See how the Launch Register workflow works.
Compare the workflow using a safe sample
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