Why SIC codes matter for prospecting
Every UK Ltd company is required to declare at least one SIC (Standard Industrial Classification) code when it incorporates. The full list of ~700 codes is maintained by the ONS, adapted from the EU NACE Rev.2 taxonomy. For accountants and bookkeepers using Companies House data for prospecting, the SIC code is the single strongest filter for narrowing down 2,500 new daily incorporations to the ~50 that are actually relevant to you.
But not all codes are equal. Some predict high-LTV clients who will pay £150+/month in fees for years. Others are used almost exclusively by shell companies, holding vehicles, and one-person side hustles that will never pay for professional services.
The 15 SIC codes that punch above their weight
Professional services (high fee tolerance, complex needs)
- 62012 — Business and domestic software development. High volume, tech-founder-heavy, they know they need a real accountant for R&D tax credits and share option schemes.
- 62020 — Information technology consultancy. Consultants tend to have complex expense claims and want proactive tax planning.
- 70229 — Other management consultancy activities. Well-paid professionals who value time.
- 71121 — Engineering design activities for industrial process. High-margin engineering consultancies.
- 73110 — Advertising agencies. Cash-heavy, multi-client billing complexity.
Trades with real overhead (worth full-service accounting)
- 41100 — Development of building projects. Property developers — VAT-heavy, CIS-heavy, high LTV.
- 41202 — Construction of domestic buildings. Same as above at smaller scale.
- 43220 — Plumbing, heat and air-conditioning installation. Growing trade with actual employees.
- 45200 — Maintenance and repair of motor vehicles. Physical assets, VAT, PAYE.
E-commerce & retail (need proper multi-channel accounting)
- 47910 — Retail sale via mail order houses or via internet. Amazon FBA, Shopify sellers — often overwhelmed by multi-channel VAT and stock accounting.
- 47990 — Other retail sale not in stores/stalls. Similar profile to the above.
Hospitality (complex, always needs help)
- 56101 — Licensed restaurants. High volume, VAT-flagged, need help with tips and PAYE.
- 56102 — Unlicensed restaurants and cafes. Same complexity, smaller ticket.
Property (recurring compliance value)
- 68100 — Buying and selling of own real estate. Deal-driven, needs help structuring transactions.
- 68209 — Other letting and operating of own or leased real estate. Property investors, SPVs, tax structuring.
Codes to skip (or heavily filter)
- 99999 — "Dormant Company". These are shell companies. Skip unless your firm specialises in structuring.
- 82990 — Other business support service activities. Too broad; use finer codes if available.
- 64209 — Activities of other holding companies not elsewhere classified. Holding vehicles — often just a legal container with no operating business.
- 96090 — Other service activities not elsewhere classified. Catch-all for anyone unsure. Low predictive value.
How to actually filter
Don't pick 40 codes. Pick 5-10 that map exactly to your existing client book. If you have three clients in one SIC code and they all pay you well, that is your signal — pick that code. If you have one struggling client in a SIC code, do not pick it just for coverage.
The advanced play: SIC + address pattern
Companies at prestigious central-London registered addresses (EC1, EC2, EC3, EC4, W1, WC1, WC2) are more likely to be either (a) high-value businesses, or (b) using a company-formation-agent service address with no real operation there. You will need to click through to a company website to tell which. Companies with a residential-looking address in a suburban postcode are far more likely to be real businesses being run by their director from home.
How Formation Alert uses this
When you subscribe to Formation Alert, you pick your SIC codes and postcode areas. Every Tuesday 8am we email you every newly-incorporated UK Ltd company that matches, with an AI-drafted one-line summary of what each looks like based on name and SIC. You spend the hour saved on outreach instead of data gathering. £49/month, 7-day free trial.