SIC Codes for UK B2B Prospecting — The Non-Boring Guide
SIC codes are the UK's free vertical-filter system. Here's which codes matter for B2B prospecting and which to ignore.
Every UK-registered company declares Standard Industrial Classification (SIC) codes when filing with Companies House. SIC codes are free, public, and updated whenever a company files a confirmation statement. Used well, they’re a fast vertical filter. Used badly, they produce false negatives.
How SIC codes work
- Each company can declare up to 4 SIC codes
- Codes are 5-digit numeric (e.g.
62012= business and domestic software development) - The hierarchy is sectional: first two digits = section, first three = division, all five = class
- Companies update codes via confirmation statement (annual) or change-of-activity filing
The most relevant SIC clusters for B2B
| Code range | Meaning |
|---|---|
| 62xxx | Computer programming, IT services — most SaaS, software, agencies |
| 70xxx | Head office + management consultancy |
| 73xxx | Advertising + market research |
| 74xxx | Other professional / scientific / technical |
| 78xxx | Employment agencies, recruitment |
| 82xxx | Office administrative + support |
| 85xxx | Education |
| 64xxx | Financial services (core finance, not fintech) |
| 66xxx | Fintech (auxiliary to finance) |
SIC code depth: going beyond the top two digits
The top two digits of a SIC code tell you the section. The full five give you much more. Reading at the five-digit level often separates your actual ICP from adjacent noise.
- 62012 vs 62020. Both sit under “computer programming, consultancy, information service activities”. 62012 is “business and domestic software development” — the classic SaaS code. 62020 is “information technology consultancy activities” — often implementation services rather than product companies. A tool targeting SaaS product companies should prefer 62012.
- 70221 vs 70229. 70221 is “financial management” consultancy. 70229 is “other management consultancy”. If you sell a finance-adjacent tool, 70221 is more specific and gives you a tighter list.
- 73110 vs 73120. 73110 is “advertising agencies”, 73120 is “media representation services”. Very different buying patterns and budgets.
- 82990. A catch-all “other business support service activities” code. If a prospect’s primary SIC is 82990, you are looking at a miscellany — could be anything. Treat as weak signal and cross-check from another angle.
Digging into the five-digit detail is free and takes a few minutes. It quietly raises the quality of the whole downstream list.
The traps
1. Multi-code fog
A company might declare 62012 (software) + 82990 (support activities). Which one are they? Often both. Don’t treat a single code as authoritative.
2. Outdated declarations
Some companies don’t update codes post-pivot. A SaaS company that started as a consultancy may still list 70229 (management consultancy) as primary. Cross-check with website + LinkedIn.
3. Over-reliance
SIC codes filter but don’t qualify. A company in the right SIC cluster can still be wrong-fit on size, stage, or region.
4. Self-declared, not verified
SIC codes are self-declared at incorporation and again at each confirmation statement. Nobody verifies them. A software-as-a-service company may have declared 70229 in haste, never updated, and still look like a consultancy in Companies House. The only reliable verification is a manual check of the company’s actual trading activity (website, LinkedIn, press).
5. Public-sector and regulated-industry codes
Certain SIC ranges (85xxx education, 86xxx healthcare, 84xxx public administration) have different buying patterns that standard B2B playbooks miss. Procurement is heavier, cycles are longer, and PECR plus additional sectoral rules apply. Factor this in before reaching out.
A worked example: building a SIC-filtered list
Imagine you sell a payroll tool to UK small accountancies. A useful SIC filter might be:
- Primary SIC: 69201 (accounting, book-keeping and auditing activities, tax consultancy).
- Secondary SIC: 69202 (bookkeeping activities).
- Exclude: 69203 (tax consultancy only, as they may have different stack patterns).
Layer the filter with Companies House revenue band (small company, £632K–£10.2M), incorporation year (at least three years old so practices are established), and region (skip if you lack licence coverage). The resulting list is typically around 2,000 UK firms, actionable for a small sales team over a year.
The whole exercise takes an hour the first time and 15 minutes to refresh quarterly. It replaces vague “UK accountancy firms” with a concrete, legally-filtered list.
How to use SIC codes in your ICP
- Define 2–4 SIC codes that match your ICP’s vertical
- Pull the list from Companies House (API + filter)
- Layer additional filters: revenue band, incorporation year, region
- Treat output as a filtered list, not a verified list — each candidate still needs website / LinkedIn cross-check
Where to look up codes
- Companies House SIC code list — official source
- ONS SIC 2007 structure — the deeper reference
Frequently asked questions
How often do companies update SIC codes? Annually at the confirmation statement, or ad-hoc via a change-of-activity filing. In practice most companies leave them unchanged unless legally required to update.
What if a company has four SIC codes all listed equally? Treat them all as directional. The Companies House “nature of business” page sometimes has additional context. The company’s own website footer and about page usually clarify the current primary activity.
Are SIC codes the same as NACE codes? Closely related. UK SIC 2007 is based on the European NACE Rev 2 system. For most B2B prospecting purposes the two are interchangeable; the digits are similar enough to translate easily.
Can we reach out to companies where SIC suggests they might buy but we are not sure? Yes, and phrase the outreach accordingly. “I noticed you are registered under [code description] — is that still your primary focus?” is a legitimate opener that turns uncertainty into conversation.
How LeadKing uses SIC codes
LeadKing uses SIC clusters as part of ICP matching. You declare vertical preferences; we filter Companies House data + signal sources accordingly. Editable per workflow.