What Is a SIC Code? The Complete UK Guide

What a SIC code is

SIC stands for Standard Industrial Classification. A SIC code is a five-digit number that classifies a business by its main economic activity — for example, software development, property letting, or running a restaurant. The system originated as a way for government statisticians to group businesses consistently, so that data about the economy could be compared across sectors and over time.

In the UK, every limited company and limited liability partnership must record at least one SIC code with Companies House. The code doesn't change what you're legally allowed to do, but it is the official, machine-readable summary of your trade. It is used by lenders, insurers, researchers, and data providers to understand which industry a company belongs to.

The UK 5-digit Condensed SIC list

The UK uses a specific version of the classification known as the Condensed SIC 2007 list. This is the authoritative set of five-digit codes that Companies House accepts. Each code maps to a single, tightly defined activity, and the list is organised into broad sections (such as information & communication, or wholesale & retail trade) that then break down into more granular categories.

Because the list is "condensed," it is a manageable subset of the full statistical classification — designed so that a company director can pick a code without needing a degree in economics. You can browse and search the full set on our SIC code lookup to find the code that best matches your activity.

Where SIC codes appear on Companies House

Once registered, a company's SIC code (or codes) is published on the public register. You'll see it on the company's overview page, and it is refreshed each year through the confirmation statement — the annual filing in which a company confirms its details are up to date.

This is why SIC codes are so useful for research: because they are public and standardised, you can filter the entire register by activity. On BizLookup, every company profile shows its SIC codes, and you can use them as a starting point to explore competitors, suppliers, or potential customers in a sector.

How to choose the right one when forming a company

When you incorporate, you'll be asked for at least one SIC code. The aim is to describe your main activity as accurately as possible. Start by writing a plain-English sentence about what your business does, then search the list for the closest match. If two codes seem to fit, choose the one that reflects the bulk of your revenue.

Avoid defaulting to a vague "other" category if a specific code exists — an accurate code makes your company easier to classify correctly by banks and credit agencies. If you genuinely can't find a precise match, the dormant and non-trading codes exist for companies that aren't yet trading. For help deciding on your wider setup, see our guide to UK company types.

Can you have multiple codes or change them?

Yes. A company can record up to four SIC codes, which is helpful if you operate across distinct activities — for instance, a firm that both develops software and provides consultancy. List them in order of importance, with your primary activity first.

You can also change your SIC codes at any time. The simplest route is to update them on your next confirmation statement, or you can file an update if your activities change significantly mid-year. There is no penalty for switching codes as your business evolves — the register is meant to reflect what you actually do.

Common SIC code examples

Here are a few of the most frequently used codes, which give a sense of how specific the list can be:

• 62012— Business and domestic software development. A common choice for software houses and SaaS startups.
• 68209— Other letting and operating of own or leased real estate. Widely used by property and buy-to-let companies.
• 47910— Retail sale via mail order houses or via the internet. The go-to code for e-commerce businesses.
• 56101— Licensed restaurants. Used by sit-in dining venues that serve alcohol.

These examples also show why SIC codes are powerful for B2B research. Because they are standardised, you can build targeted company lists by SIC code— for example, pulling every active e-commerce retailer or every software developer incorporated in a given period. That turns the public register into a practical prospecting tool.

In summary

A SIC code is a small but important detail: a five-digit label that classifies what a UK company does, recorded at Companies House and refreshed each year. Choose the most accurate code when you form your company, keep it current, and use it to research the market. Start by exploring the SIC code lookup or head back to the BizLookup homepage to search companies directly.