SIC Codes Explained: How to Choose and Change Yours

What a SIC code is and why it exists

A SIC code is a five-digit number that describes the nature of a company's business. Companies House uses a condensed version of the full list of codes maintained by the Office for National Statistics (ONS), based on the UK SIC 2007 classification. There are over 600 individual SIC codes to choose from, organised into 21 main industry sections, each denoted by a single letter from A to U.

The purpose is largely statistical. Classifying every registered company by activity lets government track industry trends and shape policy, and it gives banks, insurers and researchers a consistent way to understand what a company does. Because the code sits on the public register, it also forms part of how your company presents itself to the world, so an accurate code supports credibility with investors and lenders.

One point trips people up: Companies House will only accept codes from its condensed list. The guidance is explicit that you should only use codes on the condensed SIC code list when filing to Companies House, or your filing may be rejected. Picking a code from the wider ONS classification that is not on the condensed list is a common cause of a bounced submission.

It also helps to understand how the five digits are structured. UK SIC 2007 is a hierarchical system: the 21 top-level sections group activities broadly, and each section then narrows through divisions, groups and classes down to the five-digit code you actually file. That is why the codes look so granular. The last digits distinguish closely related activities, which is exactly what lets the register capture the real nature of a business rather than a vague label.

Where SIC codes are used: incorporation and the confirmation statement

There are two moments where SIC codes come into play. The first is at incorporation. When you register a company you have to tell Companies House what type of business you are starting, and that means choosing at least one SIC code as part of the application. You cannot complete formation without one, so it is worth deciding your codes before you begin the registration rather than pausing halfway through to search the list.

The second is the confirmation statement, which every company must file at least once every 12 months to confirm its records are up to date. The confirmation statement is the mechanism you use to report a change to your SIC codes. If your activities have shifted since incorporation or your last statement, you update the codes there so the register reflects what the business actually does now.

You are not limited to a single code. If your company provides an array of different trades or goods, you can select up to four SIC codes to describe the diverse nature of your activities. Most small companies use just one, but a business that, for example, both develops software and sells goods online may want two. If you are still at the planning stage, our company formation service walks you through the codes as part of setting the company up.

Example SIC codes across common sectors

The best way to understand SIC codes is to see real examples. The table below shows a selection of codes and their exact descriptions from the Companies House condensed list, spanning several sectors that new companies commonly fall into. Use these as a guide to the level of detail the list goes into, then search the full condensed list for the closest match to your own activity.

Notice how specific some entries are. Retail alone splits into distinct codes for shops, mail order and internet sales, and food service separates licensed restaurants from takeaways. Choosing the closest match, rather than a broad catch-all, gives the most accurate picture of your business.

Dormant and non-trading codes

A frequent question is what code to use when a company is not actually trading. Companies House is clear that you still need to provide a code even in this situation. Its guidance states that even if your company is dormant or non-trading, you still need to supply a SIC code.

There are two dedicated codes for this. Use 99999 for a dormant company, meaning one that has had no significant accounting transactions during the period. Use 74990 for a non-trading company, which covers a company that exists but is not currently carrying out business activity in the ordinary sense. Choosing the right one of the two depends on your circumstances, and if you are unsure it is worth checking the dormant company rules that govern whether your company qualifies as dormant for filing purposes.

If a dormant or non-trading company later starts trading, you would update the code to reflect the real activity at your next confirmation statement, exactly as any active company would when its activities change.

How to choose the right SIC code

Choosing a code is mostly about matching your main activity to the closest entry on the condensed list. The list is searchable, so start with a keyword that describes what you do, then read the surrounding entries to find the most precise fit rather than settling for a broad category. If your company does several genuinely different things, pick a separate code for each, up to the maximum of four.

A common mistake is reaching for a generic code such as one of the several other service activities entries when a more specific match exists. Those catch-all codes have their place, but only when nothing more precise fits. Where two codes look similar, read the full description of each and choose the one that most closely matches how the business earns its money. For a company with a clear main activity plus one or two sidelines, list the main activity first, since that is often the code third parties look at first.

Take your time here, because an inaccurate code can create friction later. Under the Economic Crime and Corporate Transparency Act, companies are expected to maintain accurate SIC codes that reflect their actual business activity, and inaccurate codes can confuse the lenders and investors who read them off the register. A few minutes spent finding the right code at incorporation saves you from having to correct the record later.

How to change your SIC codes later

Businesses evolve, and the code you chose at incorporation may no longer describe what you do. You change your SIC codes through the confirmation statement. If you need to update a code, you file a confirmation statement showing the new codes, and Companies House updates the public record accordingly.

You do not have to wait for your annual filing date. If your activities have changed and you want the register to reflect that promptly, you can file a confirmation statement early to report the updated codes. A confirmation statement carries an annual fee, but you can make multiple filings within the same 12-month payment period without paying the fee again, so an early update to your SIC codes does not necessarily cost extra.

Keeping the codes current is not just good housekeeping. Because SIC codes feed data used by Companies House, HMRC and the ONS, and shape how third parties perceive your company, an accurate code supports both compliance and credibility. If you would rather have someone handle the paperwork, our team can manage confirmation statements for you; see our plans for details.

Is a new SIC code system coming?

The classification behind SIC codes is being reviewed. In May 2026 the ONS published UK SIC 2026, with the structure and explanatory notes available and further materials, such as the main volume and indexes, to follow later in 2026. This is a newer version of the classification that currently underpins the codes Companies House uses, which are based on UK SIC 2007.

Importantly, this does not change what you file today. Companies House still uses its condensed list based on UK SIC 2007, and there is no requirement to switch. A future SIC code framework is under active discussion between Companies House and the ONS, but no final framework has yet been agreed or implemented, and any change would require legislative steps. For now, choose your codes from the condensed list as normal, and we will note any transition here when Companies House confirms one.

Conclusion

SIC codes are a small but genuinely useful part of running a UK company. They tell the world, and government, what your business does, they are mandatory at incorporation, and they can be updated whenever your activities change. The practical rules are simple: choose at least one and up to four codes, always take them from the Companies House condensed list based on UK SIC 2007, and use 99999 or 74990 if your company is dormant or non-trading.

If your activities shift, do not let the register go stale. File a confirmation statement, including an early one if needed, to bring your codes up to date, and keep them accurate to stay on the right side of the Economic Crime and Corporate Transparency Act and to present your company well to lenders and investors. Handled at the right moment, SIC codes take minutes rather than causing problems down the line.

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