Methodology

The list of UK companies, their addresses, SIC codes, status, and accounts-filing metadata comes from the Companies House BasicCompanyDataAsOneFile bulk download. The download is published on the first Sunday of each month, covering all ~5.8M registered companies.

Rather than ingest this file directly, we replicate a read-only subset from the canonical store on our sister site (ukcompanyfinder.com) which already runs the monthly ingest. A weekly cron pulls the latest snapshot into this site's Postgres. This keeps the two sites' base data in sync without duplicating the ingest pipeline.

Charges, officers/PSCs, and insolvency events are not in the bulk file. They live on the Companies House Public Data API and are fetched on first view of a company page, then cached for seven days. Subsequent views serve from cache.

We respect the API rate limits (600 requests / 5 minutes per IP) and back off gracefully under bursts.

Every active UK company files accounts under one of four regimes:

• FRS 105 (micro): turnover under £632k, balance sheet under £316k, fewer than 10 employees.
• FRS 102 Section 1A (small): turnover up to £10.2M, balance sheet up to £5.1M, fewer than 50 employees.
• FRS 102 full: above the small ceiling, typically turnover up to £36M.
• FRS 102 full or IFRS (large): turnover above £36M.

Each regime has a strict turnover ceiling set by the Companies Act 2006. So the regime a company filed under is, by definition, a bound on its turnover — without any modelling.

We use the accounts_category field from Companies House to assign every active company to a band. Companies that have never filed (newly incorporated or non-trading) appear as "unclassified" until their first filing lands.

For the ~200-300k companies that file full FRS 102 or IFRS accounts in iXBRL format, the actual turnover number is publicly filed. Parsing those filings is a planned addition; for now we display only the size band and link to the filing on Companies House.

• Each company page links to its registry record on ukcompanyfinder.com (and to find-and-update.company-information.service.gov.uk for the official source).
• Officers are cross-referenced by normalised name + year of birth. The "other UK companies" count on each officer is computed across the full officers table.
• SIC codes link to per-sector pages; town and postcode fields link to per-place pages.

• Base companies: weekly (Sundays, after Companies House publishes).
• Charges / officers / insolvency: lazy-loaded; cached 7 days.
• SIC code reference list: monthly.
• Sitemap: regenerated daily.

• We do not estimate revenue for companies that haven't disclosed one. We display only the band that their filing regime bounds them within.
• We do not modify, supplement or interpret Companies House data beyond surfacing it with cross-references.
• We are not Companies House. Authoritative records are at find-and-update.company-information.service.gov.uk.