A Standard Industrial Classification (SIC) code is a five-digit identifier that categorises the principal business activity of your UK company. Every limited company registered with Companies House must declare at least one SIC code, which enables government bodies, lenders and business intelligence platforms to understand what your company does. Choosing the correct code ensures regulatory compliance, supports accurate industry statistics and can influence how lenders and funding bodies assess your eligibility for grants and finance.

What does SIC stand for and why does it exist?

SIC stands for Standard Industrial Classification. The system was developed to provide a consistent framework for collecting, analysing and presenting economic data across all sectors of the UK economy. The Office for National Statistics uses SIC codes to track industry growth, employment trends and sectoral productivity.

For Companies House, SIC codes serve a dual purpose: they classify businesses for public record and they feed into data used by government bodies, including HMRC and the Office for National Statistics, to track industry trends and inform policy. Because the code appears on your public company record, suppliers, customers and potential partners also use it to verify the nature of your business.

There are over 700 distinct five-digit codes spanning every conceivable commercial activity, from agriculture and mining to digital services and creative industries. Companies House filings still use a condensed list based on UK SIC 2007, which aligns with the European NACE Rev. 2 classification. The ONS has since published UK SIC 2026 (aligned with NACE Rev. 2.1 and effective from 14 April 2026), but Companies House has not adopted it and says any change would need new legislation.

How the five-digit SIC hierarchy works

The SIC system is hierarchical, meaning each digit adds a layer of specificity:

  • Section (letter): The broadest category, such as Section C for Manufacturing or Section M for Professional, Scientific and Technical Activities. This letter does not form part of the five-digit code but helps you navigate the structure.
  • Division (first two digits): Defines the general industry area. For example, Division 62 covers Computer Programming, Consultancy and Related Activities.
  • Group (first three digits): Narrows the focus further. Division 62 contains a single group, 620 (computer programming, consultancy and related activities); data processing sits in a separate division, as Group 631 within Division 63.
  • Class (first four digits): Identifies a more specific business type. Class 6201 refers specifically to computer programming activities.
  • Subclass (all five digits): The complete code you declare to Companies House. Code 62012, for instance, denotes business and domestic software development as distinct from other programming work.

When you search the official SIC code list on the Companies House website, enter keywords that describe your main activity or browse the hierarchical tree. Always select the most precise five-digit code that matches your principal revenue-generating activity.

How to choose the correct SIC code for your company

Selecting the right code requires you to identify what your business does, not merely what it sells. A common mistake is choosing a code based on the product you offer rather than the activity that generates your income.

Step-by-step selection process:

  1. Visit the condensed SIC code list published by Companies House on GOV.UK.
  2. Identify the section letter that broadly describes your industry (for reference only - you will not file this letter).
  3. Drill down through divisions and groups using keywords related to your primary business activity.
  4. Select the five-digit subclass code that most accurately reflects how your company earns the majority of its revenue.
  5. If your business operates across multiple distinct activities, you may declare up to four SIC codes. Make sure one of them describes your main activity.

Practical examples:

  • An accountancy practice would typically use 69201 (Accounting and auditing activities).
  • A general building contractor would select 41201 (Construction of commercial buildings) or 41202 (Construction of domestic buildings), depending on the primary client base.
  • A freelance graphic designer operating through a limited company might choose 74100 (Specialised design activities).
  • A company that both manufactures furniture and sells it at retail would declare the manufacturing code (e.g. 31010 for office furniture) as primary if that activity drives the majority of turnover, and optionally add a retail code as secondary.

Avoid choosing a code simply because it sounds aspirational or because competitors use it. HMRC and Companies House expect your SIC code to reflect your actual, current trading activity.

When and where you need to provide a SIC code

You must declare at least one SIC code in the following situations:

  • Company formation: When you incorporate a new limited company, the incorporation form (IN01 or online equivalent) requires you to state your intended business activity via one or more SIC codes.
  • Confirmation statement: Every company must file an annual confirmation statement (formerly the annual return) with Companies House. This statement includes your current SIC code(s) and offers an opportunity to update them if your activities have changed.
  • Dormant companies: Even if your company is not trading, you must still declare a SIC code. Companies House's condensed list includes 99999 (Dormant Company) and 74990 (Non-trading company) for this, but switch to a code that reflects your actual activity once you start trading.
  • VAT registration: HMRC's VAT registration application asks for the SIC code that best describes your business activities, and your Companies House record - including your SIC code - is visible to HMRC and may inform compliance checks and industry benchmarking.

Sole traders and unincorporated partnerships are not required to register with Companies House and therefore do not need a SIC code for statutory purposes. However, they may be asked to provide one when applying for business bank accounts, grants or trade credit.

How to change or update your SIC code

Business activities evolve. You may pivot into a new market, diversify your service offering or cease one activity in favour of another. When your principal business activity changes, you should update your SIC code to maintain an accurate public record.

How to update your code:

  1. Log in to your Companies House account or use the online confirmation statement service.
  2. Review the current SIC code(s) listed for your company.
  3. Amend or add codes as necessary, ensuring the primary code reflects your main revenue-generating activity.
  4. Submit the confirmation statement. You may need each director's identity verification personal code to file it. The updated SIC code(s) will appear on your public company record once Companies House has accepted the statement.

There is no separate fee for changing your SIC code. The confirmation statement fee (£50 online, £110 by post) is paid with the first statement in each 12-month payment period, and any further statements in that period are free. You are not required to wait until your annual confirmation statement is due; you can file an early statement at any time to update your details.

Keeping your SIC code current is not merely good housekeeping. An outdated or incorrect code can lead to missed grant opportunities, misclassification by lenders and confusion among potential clients or partners who rely on Companies House data.

Why your SIC code matters beyond compliance

While the immediate reason to choose a SIC code is to satisfy Companies House requirements, the code has several practical implications:

Access to finance: Banks and alternative lenders use SIC codes to assess sector risk, benchmark your financial ratios against industry norms and determine lending appetite. A precise, appropriate code can improve your chances of securing a business loan or overdraft facility.

Grant and relief eligibility: Many government grants and innovation funds target specific industries. Lenders and funding bodies use SIC codes to assess eligibility, but tax reliefs depend on what your company actually does: research and development (R&D) relief, for example, turns on whether a project seeks an advance in science or technology, not on your SIC code.

Regulatory oversight: Certain activities carry additional regulatory obligations. For instance, companies in financial services, healthcare or food production may face sector-specific reporting, licensing or inspection requirements. These obligations arise from the activity itself, not from the SIC code you declare, so choosing a code does not by itself make you compliant.

Market intelligence and networking: Business directories, procurement platforms and industry associations filter companies by SIC code. An accurate code makes your company discoverable to potential clients, suppliers and partners searching for businesses in your sector.

Statistical accuracy: The Office for National Statistics, trade bodies and economic researchers rely on SIC data to measure sectoral performance, employment trends and productivity. Accurate classification contributes to better policy-making and industry benchmarking.

Common mistakes to avoid when selecting a SIC code

Many newly incorporated companies choose a SIC code hastily or based on incomplete information. Here are the most frequent errors:

  • Choosing by product rather than activity: If you manufacture software, your code should reflect software development (62012), not retail sale of software (47410), even if you sell directly to end users.
  • Selecting an aspirational code: Declare the activity you are currently engaged in, not the one you hope to pursue in future. You can always update your code when your business model changes.
  • Using multiple unrelated codes: While you may declare up to four codes, they should all relate to genuine, ongoing business activities. Adding codes speculatively can confuse stakeholders and dilute your company's perceived focus.
  • Ignoring the condensed list: Companies House only accepts codes from the official condensed SIC list published on GOV.UK. Do not invent codes or use outdated versions from unofficial sources.
  • Failing to update after a pivot: If your business model changes significantly - for example, from consultancy to product manufacturing - update your SIC code promptly via a confirmation statement.

Who is exempt from providing a SIC code?

The requirement to declare a SIC code applies exclusively to entities registered with Companies House. The following are not required to provide a SIC code:

  • Sole traders: Unincorporated self-employed individuals do not register with Companies House and therefore have no statutory SIC code obligation, though they may be asked for one by banks or grant providers.
  • General partnerships: Traditional partnerships (excluding limited liability partnerships) are not registered with Companies House and do not file SIC codes.
  • Limited liability partnerships (LLPs): LLPs are registered with Companies House but, under current rules, are not required to declare a SIC code on their public record. However, this may change, so always check the latest guidance on GOV.UK.

If you operate as a limited company, you must declare at least one SIC code, regardless of whether you are trading, dormant or newly incorporated.

Frequently asked questions

Can I change my SIC code after incorporation?

Yes. You can update your SIC code at any time by filing a confirmation statement with Companies House. There is no extra fee if you have already paid the confirmation statement fee for the current 12-month payment period, and the change takes effect once Companies House accepts the statement. If your business activities have shifted, update your code to reflect your current primary activity.

How many SIC codes should I choose?

Most companies declare one primary SIC code. If your business genuinely operates across multiple distinct activities - for example, both manufacturing and wholesale distribution - you may declare up to four codes. Make sure one of them covers your main source of revenue.

What happens if I choose the wrong SIC code?

An incorrect SIC code can cause delays with lenders and funding bodies, missed grant opportunities and confusion among partners. Companies House can now challenge, reject or remove information that looks wrong, so a code that doesn't match your actual activity can lead to filing rejections or delays while it investigates. If you realise you have selected the wrong code, file a confirmation statement to correct it as soon as possible.

Do I need a SIC code if my company is dormant?

Yes. Even dormant companies must declare a SIC code when filing their confirmation statement. Companies House's condensed list includes 99999 (Dormant Company) and 74990 (Non-trading company) for this purpose; once the company starts trading, switch to a code that reflects its actual activity.

Where can I find the official SIC code list?

The authoritative source is the condensed SIC code list published by Companies House on GOV.UK. You can search by keyword or browse the hierarchical structure. Do not rely on third-party websites or outdated lists, as only the official condensed list is accepted for company filings.

Will my SIC code affect my tax liability?

Your SIC code itself does not determine your tax rate or your eligibility for reliefs: R&D relief, creative industry reliefs and capital allowances depend on what your company actually does and spends, not on the code you declare. Always consult HMRC guidance or speak to a qualified accountant if you believe your sector qualifies for special treatment.

How MPS Accountancy can help with company formation and compliance

Choosing the correct SIC code is a small but important step in setting up and maintaining your limited company. At MPS Accountancy, we can help you choose the right structure, register with Companies House and HMRC, and then keep your accounts, tax and compliance on track so your Companies House records stay accurate and up to date.

Whether you are incorporating a new venture, pivoting an existing company or simply reviewing your confirmation statement, our team can advise on the most appropriate SIC code for your activities and help you avoid common pitfalls. We also provide annual accounts preparation, corporation tax return filing and strategic tax planning to keep your company compliant and tax-efficient.

If you would like expert guidance on SIC codes, setting up a company or your annual compliance, get in touch with our team for a no-obligation consultation.