Published 14 August 2026 · updated 9 September 2026 · 4 min read
A SIC code is a standard industrial classification describing the company's activity. You give at least one at incorporation, and you can give up to four. Most people choose in seconds from a dropdown and never think about them again.
Who reads them
- Banks. Onboarding checks compare your SIC codes against what you say you do. A mismatch is a common reason an application stalls.
- Insurers. Cover is priced and sometimes refused on the basis of activity.
- Lenders and credit agencies. Sector influences credit scoring.
- Anyone doing due diligence. Customers, landlords, procurement teams.
How to choose well
Pick the code that describes what generates your revenue, not what you aspire to do. If you sell software, "computer programming activities" is the honest answer even if you describe yourself as a consultancy. Add secondary codes only for activities you actually carry on.
Codes to avoid unless they are true
Some codes attract scrutiny — those covering financial intermediation, money transfer, cryptocurrency, and general "other business support activities", which reads as "we did not want to say". Choosing one of these when it does not apply invites questions you did not need.
Changing them
SIC codes are updated on the confirmation statement, so at least once a year you get a free opportunity to correct them. If what you sell has drifted from what you registered, take it.
Dormant companies
There is a specific code for a dormant company. Using it while actively trading, or leaving a trading code on a genuinely dormant company, both create the same problem: the register says something different from the accounts.
Nothing here is advice about your situation
It is general information about how UK company registration works, written to be accurate at the time of publication. Rules and fees change. Where a decision matters — tax, structure, an insolvent company — take advice on your own facts.