UK SIC Codes Explained (Companies House)

SIC codes are one of the most powerful ways to filter UK companies by industry.

SIC stands for Standard Industrial Classification. In the UK, companies provide SIC codes to Companies House to describe their nature of business / economic activity.

Using SIC codes in firmlist helps you:

• target specific industries (high relevance)
• reduce noise compared with keyword searches
• build repeatable segments (e.g., "UK accountants", "UK plumbers", "UK software firms")

What is a SIC code?

A SIC code is a 5-digit code describing what a company does. Companies House uses a condensed SIC 2007 list for filings.

UK SIC 2007: how the classification is structured

UK SIC (2007) is hierarchical and supports consistent classification across the economy. At a high level it is organised into sections (A-U), then subdivided into divisions, groups, classes and subclasses.

Why SIC codes matter for B2B lead generation and research

1) Precision beats keywords

Text search can be messy: businesses use varied wording on websites and filings. SIC codes let you target the official activity classification recorded on the public register.

2) Repeatable segmentation

Once you identify the right SIC codes, you can consistently build segments like:

• Construction companies
• Retailers
• Software development businesses
• Accountancy firms

3) Combine SIC with other filters for "laser" targeting

SIC codes work best alongside:

• Company status (active/dissolved/insolvency)
• Company type (LTD vs LLP, etc.)
• Location (postcode prefix, region)
• Incorporation date (newly formed vs established)

How to find the right SIC code(s)

Use the official condensed list

Companies House provides a condensed SIC code list used for filings. See: Companies House SIC codes.

Use the ONS hierarchy for deeper exploration

ONS provides tools and documentation to explore the hierarchy. See: ONS SIC hierarchy view.

Single vs multiple SIC code filtering (how to think about it)

When to filter by a single SIC code

Use this when you need a tight list and high relevance.

When to filter by multiple SIC codes

Use this when your buyers span multiple related activities.

Rule of thumb: choose codes that represent adjacent real-world buying behaviour, not every vaguely related category.

Common pitfalls (and how to avoid them)

SIC codes can be imperfect

SIC codes are self-declared at incorporation/filing. Some firms choose broad codes or don't update them when their business changes. Use SIC codes as a strong starting filter, then refine using other filters and sampling.

Browse by industry

Instead of searching SIC codes manually, explore pre-built industry segments:

Browse all industries →

Related guides

• Company Types Explained
• Company Status Explained
• Company Numbers & prefixes
• Postcode & location filtering
• Company age & incorporation date
• Other indicators

Sources (further reading)

• Companies House - SIC codes
• GOV.UK - Standard Industrial Classification
• ONS - UK SIC 2007
• ONS - SIC hierarchy view
• ONS - UK SIC 2007 (PDF)