A SIC code is a five digit Standard Industrial Classification code that tells Companies House, and anyone searching the register, what a company actually does. Companies House only accepts codes from its condensed version of the UK SIC 2007 list, the paper confirmation statement has room for four, and the only way to change them after incorporation is to send the change with a confirmation statement.

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What is a SIC code and which list does Companies House use?

The Standard Industrial Classification is the Office for National Statistics framework for classifying businesses by the economic activity they carry on. The ONS describes it as a framework for collecting and analysing data that can also be used for administrative purposes. The version Companies House uses is UK SIC 2007.

Companies House does not use the full ONS structure. It publishes a condensed list of five digit codes, and its guidance says you should only use codes on that condensed list when filing, or your filing may be rejected. The list currently runs to 731 codes, each with a short description, from 01110 for growing cereals through to 99999 for a dormant company.

The ONS has now published a new framework, UK SIC 2026, effective from 14 April 2026. It is not yet in operational use: the ONS expects to introduce it gradually, with the first use planned for the 2031 Blue Book. Until Companies House says otherwise, keep using its 2007 condensed list.

What does the law actually require?

The application to register a company must include a statement of its intended principal business activities under section 9(5)(c) of the Companies Act 2006, and section 9(5B) allows that information to be given by reference to a prescribed classification system. That is where the first SIC codes come from.

After incorporation, section 853C applies. If a company’s principal business activities have changed during the confirmation period, it must notify the registrar of the change at the same time as it delivers its confirmation statement. Section 853C(3) again lets the new activities be described by reference to one or more categories of the prescribed classification. Since 4 March 2024, section 853C(1A) also catches a company whose activities had already changed between the incorporation application and the moment of incorporation; that change goes in with the first confirmation statement.

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How many SIC codes can a company have?

Part 1 of the paper confirmation statement (the CS01 additional information page) has four boxes for new SIC codes and four boxes for codes that no longer apply. In practice, four codes is the working maximum and most small companies need only one or two.

The legal test is principal business activities, not every activity. A consultancy that occasionally resells equipment does not need a retail code. If the company genuinely runs two or three distinct lines of business, list each one; if it runs one, list one. Where you cannot find a fitting code, the CS01 allows a brief written description of the main business activity instead.

How do you choose the right code?

Start from what generates the income, not from the company name or what the founders hope to do eventually. Then search the condensed list using several words that describe the activity. Some points to watch:

  • Professional services are split finely. Accounting and auditing (69201), bookkeeping (69202) and tax consultancy (69203) each have their own code, as do information technology consultancy (62020) and management consultancy other than financial management (70229).
  • Property companies need care. Buying and selling own real estate (68100) is a different activity from letting and operating own or leased real estate (68209). A buy to let company and a developer that sells what it builds are not the same, and residents property management (98000) is different again.
  • Holding companies have their own codes. Activities of other holding companies n.e.c. (64209) and activities of head offices (70100) describe group structures better than the trade of the subsidiaries.
  • Dormant and non trading companies. The condensed list includes 99999 for a dormant company and 74990 for a non trading company.
  • Catch all codes are a last resort. Codes ending “n.e.c.” (not elsewhere classified), such as 82990 or 96090, are there for activities that genuinely fit nowhere else.

The ONS stopped answering individual requests to assign SIC codes from 20 September 2019, so the decision is yours or your adviser’s.

How do you change SIC codes on the confirmation statement?

There is no standalone form for changing a SIC code. You change it through the additional information section of the confirmation statement, either online or on paper form CS01, and the change must be sent at the same time as the statement itself.

  1. Check the codes currently shown on the company’s register entry.
  2. Pick the new code or codes from the condensed list.
  3. File the confirmation statement, adding new codes and removing those that no longer apply.

You do not have to wait for the confirmation date. Companies House guidance allows a confirmation statement to be filed early, in which case you choose a new confirmation date and the next review period starts the day after it. The annual fee is paid only with the first confirmation statement in each 12 month payment period, so a second statement in the same payment period is free. Currently the fee is £50 online and £110 on paper.

If the company is not yet due and has already paid this year’s fee, an early statement is a cheap way to correct a wrong code straight away. If the fee has not yet been paid for the current payment period, filing early simply brings forward a fee you would have paid anyway.

The confirmation statement must still be complete in other respects. Changes to directors, PSCs, registered office and registered email address must be filed before it, and Companies House will not accept a confirmation statement until all directors have verified their identity. See the confirmation statement explained and identity verification for Companies House.

Why does an accurate SIC code count?

The nature of business is shown free of charge on every company’s public register entry, and Companies House’s advanced search lets anyone filter companies by SIC code. Lenders, suppliers, researchers and journalists use those searches, and a code that misdescribes the company sends them the wrong message.

There is also a legal edge. Under section 1112 of the Companies Act 2006 it is an offence, without reasonable excuse, to deliver a document or make a statement to the registrar that is misleading, false or deceptive in a material particular. A genuine judgement call between two plausible codes is not the target, but deliberately choosing a code to disguise what a company does is a different matter. See false statements to Companies House.

The code also follows the company into other notices. For example, when an administrator is appointed the Gazette notice must state the nature of the company’s business under rule 3.27 of the Insolvency (England and Wales) Rules 2016. See what a Gazette notice about your company means.

How might this play out?

Illustration only. A company was formed in March 2023 with code 62020 for IT consultancy. By 2026 its founder has stopped consulting and the company owns and lets three flats. Its payment period runs from March each year and it paid this year’s fee with a confirmation statement filed in March 2026, so its next confirmation statement is not due until March 2027.

In June 2026 a mortgage lender asks why the register still describes an IT consultancy. The directors file an early confirmation statement in June, choose a June confirmation date, add 68209 and remove 62020. No fee is due because the fee for the current payment period has already been paid. Their next review period now runs from the day after the June confirmation date.

What mistakes come up most often?

  • Using a code from the full ONS index or from a foreign classification that is not on the Companies House condensed list, which risks rejection.
  • Leaving the incorporation code unchanged for years after the business has moved into a different activity.
  • Listing every minor activity rather than the principal ones.
  • Forgetting to remove old codes when adding new ones, so the register shows activities the company stopped years ago.
  • Leaving 99999 in place once a dormant company starts trading, or failing to update the code when a trading company becomes dormant.
  • Waiting for the next confirmation date when an early statement would fix the record sooner. See filing a late confirmation statement for what happens if the statement itself is overdue.

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Related Accountapedia entries

See also: IN01: registering a company on paper or online.

Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.