This guide is maintained as a current resource for September 2026 and covers only the laws of England and Wales. Information is for general guidance, not legal advice. Consult a qualified solicitor for advice specific to your situation.
Discover how Standard Industrial Classification (SIC) codes are used when forming a company in England and Wales, why they are required by Companies House, how to choose appropriate codes, update them with confirmation statements, and the practical implications for business classification and compliance.
When a company is formed in England and Wales, it must provide certain information about its structure and activities to Companies House, the UK's registrar of companies. One of the key pieces of data required at formation is a Standard Industrial Classification (SIC) code - a numerical classification that describes the nature of the company's principal business activity. SIC codes are used by government departments, economic analysts and financial institutions to organise, compare and analyse business activity across the UK economy.
This article explains what SIC codes are, why they matter at company formation, how to select appropriate codes, what happens if activities change, and answers common questions about their legal and administrative significance.
What Are SIC Codes?
A Standard Industrial Classification (SIC) code is a five‑digit numerical code used to classify business activities according to a recognised framework maintained by the Office of National Statistics (ONS) and used by Companies House. The codes cover a wide range of economic activities, grouped into broad sectors such as agriculture, manufacturing, professional services and retail.
The purpose of SIC codes is to:
- Provide a standardised description of each company's primary activities.
- Support the collection and analysis of economic data by the UK government and agencies such as HM Revenue & Customs (HMRC).
- Enable consistent classification of companies on the public register for statistical reporting and economic research.
- Assist third parties such as insurers, banks and analysts in understanding a company's line of business.
Companies House uses a condensed list of SIC codes drawn from the broader ONS classification system, and only codes from that list should be used when filing incorporation documents and later reports.
Why SIC Codes Matter at Formation
For all limited companies, SIC codes are mandatory at the point of incorporation. When you complete your company registration with Companies House - whether online or by post - you will be asked to enter at least one SIC code to describe what your business does. This obligation applies even if the company is dormant (inactive) or not yet trading. In these cases, specific codes such as 99999 (dormant company) or 74990 (non‑trading company) are available.
SIC codes perform an informational and administrative role rather than imposing any direct legal limitation on what your company can do. They do not restrict the company's objects or legal powers - unlike historic “objects clauses” under older company law - but they must accurately reflect your principal activities as described at formation.
How to Choose SIC Codes
Minimum and Maximum Number of Codes
At company formation, you must provide at least one SIC code but may include up to four codes if your business engages in multiple activities that are best described by different codes. Providing multiple codes allows a more complete picture of your business operations for statistical and administrative purposes.
Finding the Right Codes
The full list of SIC codes and their descriptions is available through Companies House and the condensed list endorsed for UK companies. Codes are organised into major categories based on industry sectors, ranging from Section A: Agriculture, Forestry and Fishing to Section U: Activities of extraterritorial organisations and bodies.
To find the most appropriate SIC code for your business:
- Review the condensed list of SIC codes on the Companies House website.
- Match your core business activities to the closest descriptions.
- If your business engages in several types of work (for example, software development and consultancy), select additional codes to cover secondary activities.
- Consult a company formation specialist, accountant or adviser if you are unsure.
It is important to use a code that accurately reflects your business because incorrect SIC codes can cause issues with banks, insurers and regulators who rely on this information when assessing risk, eligibility for finance or compliance obligations.
How SIC Codes Are Used After Formation
Once submitted at formation, SIC codes become part of your company's public record maintained by Companies House. They are visible in your company's overview and are passed to the ONS and other agencies to support economic analysis.
Annual confirmation statements - the annual filing that keeps your company's basic details up to date - require you to confirm or update your SIC codes. If your business activities change, you can amend your SIC codes by filing an early confirmation statement, rather than waiting for the next annual filing window. This helps ensure that public records and statistical databases remain accurate.
Dormant and Non‑Trading Companies
Even if a company has no current business activity, it must still supply a SIC code on incorporation. Specific codes exist for these situations:
- 99999 - Dormant company (no significant accounting transactions).
- 74990 - Non‑trading company (no trading activity but not classified as dormant).
Choosing the correct code ensures that your company is properly classified for statistical and administrative purposes from the outset.
Legal and Practical Considerations
No Legal Limitation, but Administrative Accuracy Matters
SIC codes do not impose legal restrictions on what your company may do in the future. Under the Companies Act 2006, companies generally have unrestricted objects unless their articles specifically limit them. The SIC code is purely descriptive and used for classification and reporting.
However, using the wrong code can complicate dealings with third parties. For example, banks and insurers often use SIC codes when assessing credit risk, underwriting policies or evaluating loan applications. An inaccurate code may lead to incorrect risk profiling or even invalidation of insurance if the insurer believes the code misrepresents your business.
Keeping SIC Codes Updated
If your business evolves, it is good practice to update your SIC codes to reflect new activities. You do this by submitting a confirmation statement with updated codes to Companies House. This ensures your public record is current and reduces the likelihood of misunderstandings or misclassification by data users.
Risks of Incorrect SIC Codes
Failing to provide any SIC code at incorporation will cause your incorporation application to be rejected by Companies House. Even after incorporation, failing to update SIC codes when your business changes can mislead stakeholders or affect your company's access to services, finance and regulatory compliance. It may also lead to discrepancies in statistical data collected by government agencies.
Common Questions
Do I have to use a SIC code when forming a UK company?
Yes. Every company incorporated in England and Wales must provide at least one SIC code when registering with Companies House, even if it is dormant or not yet trading. Failure to supply a valid code will lead to rejection of the incorporation application.
Can I use more than one SIC code?
Yes. A company may provide up to four SIC codes at formation to describe multiple business activities or lines of work.
Can SIC codes limit what my company can do?
No. SIC codes are descriptive, not restrictive. They do not legally constrain your company's activities but help classify what it does. Your company can undertake activities beyond those implied by the codes unless its articles expressly restrict its objects.
How do I change SIC codes if my business changes?
You update SIC codes when you file your annual confirmation statement with Companies House. You may file an early confirmation statement if you want the new codes reflected sooner.
Key Takeaways
Standard Industrial Classification (SIC) codes are essential information for companies incorporated in England and Wales. These five‑digit codes describe a company's principal and secondary activities for classification, reporting and statistical purposes. They must be provided at formation, using a recognised condensed list from Companies House, and may be updated in annual confirmation statements. While SIC codes do not legally constrain a company's activities, accurate selection at formation and subsequent updates support compliance, reliable public records, and smooth interactions with banks, insurers and government bodies. Understanding and selecting appropriate SIC codes helps present a clear picture of your business on the UK public register and contributes to broader economic analysis.
