SIC Codes Explained: How Accountants Can Use Them to Target the Right Companies
A practical guide to the UK's industry classification system — what SIC codes are, how they work, and how to use them to filter new companies by sector.
If you've ever looked up a company on Companies House, you've seen a SIC code, even if you didn't pay it much attention. SIC codes are the UK's standard system for classifying what a company does. Every limited company is assigned at least one when it incorporates. For accountancy practices, they're one of the most practical tools available for filtering new companies by sector.
This guide covers what SIC codes are, how they're structured, which ones matter most for accountant targeting, and where their limitations lie. If you're setting up filters for the first time or wondering whether SIC codes are reliable enough to bother with, this is the place to start.
What SIC Codes Are
SIC stands for Standard Industrial Classification. It's the UK's system for categorising business activities into a structured, hierarchical code system. The current version is the 2007 SIC code framework, which is based on the European NACE Rev. 2 classification.
Every company registered at Companies House has at least one SIC code on its record. The code describes the company's primary business activity or, more precisely, the activity the directors said the company would carry out when they incorporated it.
SIC codes are one of several data fields available from the day of incorporation. For a broader view of what's on the register, see our Companies House data guide.
How SIC Codes Work
SIC codes are hierarchical. They start broad and get more specific as you add digits. The structure runs from section (a single letter) down to subclass (a five-digit code):
- Section — the broadest category, identified by a letter. For example, Section M covers "Professional, Scientific and Technical Activities."
- Division — a two-digit code. Division 69, within Section M, covers "Legal and Accounting Activities."
- Group — a three-digit code. Group 69.2 narrows to "Accounting, Bookkeeping and Auditing Activities; Tax Consultancy."
- Class — a four-digit code. Class 69.20 is the specific class for accounting and auditing.
- Subclass — a five-digit code. Subclass 69201 identifies "Accounting and Auditing Activities" specifically.
Worked example: If your practice serves construction sector clients, you'd start at Section F (Construction), look at Division 41 (Construction of Buildings), and could filter as broadly as the whole division (41) or as narrowly as subclass 41201 (Construction of Commercial Buildings). Broader codes capture more companies; narrower codes give you more precise targeting.
How They're Assigned
When directors incorporate a new limited company, they choose one or more SIC codes from the official list to describe the company's business activity. This is self-selected. Companies House do not verify or audit the choice.
That distinction matters. A director incorporating a management consultancy might choose SIC code 70229 ("Management Consultancy Activities other than Financial Management"), or they might choose something more generic. There's no penalty for choosing a broad code, and no review process to check the selection. This is one of the system's practical limitations.
A company can list up to four SIC codes to describe its activities. In practice, many new companies list just one.
SIC Codes Accountants Should Know
Companies House uses a condensed version of the standard UK SIC 2007 list — fewer entries, some with descriptions that differ slightly from the ONS original. The full Companies House list still runs to hundreds of codes. You don't need all of them. Below is a selection commonly relevant to accountancy practices, grouped by sector. Use this as a starting point — not an exhaustive list.
Professional services: 69201 (Accounting and auditing activities), 69202 (Bookkeeping activities), 69203 (Tax consultancy), 70229 (Management consultancy activities), 74909 (Other professional, scientific and technical activities).
Construction: 41100 (Development of building projects), 41201 (Construction of commercial buildings), 41202 (Construction of domestic buildings), 43110 (Demolition), 43290 (Other construction installation).
Technology and digital: 62011 (Ready-made interactive leisure and entertainment software development), 62012 (Business and domestic software development), 62020 (Information technology consultancy activities), 62090 (Other information technology service activities).
Retail and e-commerce: 47110 (Retail sale in non-specialised stores), 47910 (Retail sale via mail order or internet).
Health and care: 86210 (General medical practice activities), 86220 (Specialist medical practice activities), 86900 (Other human health activities).
Property: 68100 (Buying and selling of own real estate), 68209 (Other letting and operating of own or leased real estate), 68310 (Real estate agencies).
The authoritative reference for codes used in company filings is the Companies House SIC code list, available on the Companies House website. The ONS publishes the underlying UK SIC 2007 standard separately, but the two are not identical.
Using SIC Codes to Target New Companies
SIC codes become genuinely useful when you combine them with new incorporation data. Every company that incorporates selects its SIC codes on day one, which means you can filter the daily flow of new incorporations by sector from the start.
The practical approach is to combine SIC code filtering with location filtering (using postcode areas) to produce a focused, relevant list. A practice in Leeds specialising in tech clients, for example, might filter for SIC codes 62011–62090 in the LS postcode area. The result is a short, manageable list of new companies that match both the sector and the geography you serve. .
SIC codes are just one of several fields available at incorporation. Paired with the registered address, company name, and director names, they give you enough context to decide whether a new company is worth reaching out to. .
Filter New Incorporations by SIC Code
As part of LaunchRegister account creation you can set your preffered SIC Codes as search profile to deliver matched new companies to your inbox, daily or weekly.
See how it worksLimitations to Be Aware Of
SIC codes are useful, but they're not perfect. Being honest about the limitations helps you use them more effectively.
Self-selected, not verified. Directors choose their own SIC codes at incorporation. Some choose carefully; others pick the first code that looks roughly right. There's no review process and no consequence for choosing a generic code.
Generic codes are common. SIC code 82990 ("Other Business Support Service Activities Not Elsewhere Classified") is a catch-all that a wide range of companies end up under. If your target sector is specific, you'll occasionally miss companies that chose a vague code, and occasionally pick up companies that don't quite fit.
Activities evolve. A company's SIC code reflects what the directors intended at incorporation. If the business pivots, for example a consultancy that starts offering training, the SIC code may not be updated. For established companies, the code can be out of date. For new companies, it's usually a reasonable indicator.
The practical takeaway: treat SIC codes as a useful starting filter, not a guarantee. They'll get you most of the way there. Combine them with location filtering and a quick review of each company name, and you'll have a reliable enough shortlist to work from.
Frequently Asked Questions
What is a SIC code?
A Standard Industrial Classification code that describes a company's business activity. Every UK company is selects at least one SIC code at incorporation. The codes follow a hierarchical structure, from broad industry sections down to specific five-digit subclasses.
Who assigns the SIC code?
The company's directors choose the SIC code (or codes) when incorporating. It's a self-selection. Companies House do not verify or audit the choice. This means SIC codes are a useful indicator of business activity, but not a guarantee.
Can a company have more than one SIC code?
Yes. A company can list up to four SIC codes to describe its activities. In practice, many new companies list just one. Multiple codes are more common when a company operates across distinct sectors.
How do I find the right SIC codes for my targeting?
Start with the broad division (two-digit code) for your target sector, then narrow to specific groups or classes as needed. The table earlier in this guide covers the most common codes for accountant targeting. .
Are SIC codes always accurate?
Not always. Because they're self-selected, directors sometimes choose a generic code or one that doesn't precisely match their activity. SIC code 82990 ("Other Business Support Service Activities") is a common catch-all. Treat SIC codes as a useful starting filter, not the sole criterion for your targeting.
Put SIC Codes to Work
Know which sectors you want to target? The next step is combining SIC codes with location filters to build a focused shortlist. .