Every UK limited company must hold at least one Standard Industrial Classification (SIC) code on the Companies House register. When a company’s activities change, or when the original code no longer reflects what the business does, directors need to know how to change a SIC code and where that process sits within the company’s compliance obligations. This article explains the process, why accuracy matters, and what can go wrong when the wrong code is left in place.
- The only way to change a SIC code is via the confirmation statement; there is no separate Companies House form or service for SIC amendments.
- An early confirmation statement can be filed solely to fix a SIC code without resetting the 12‑month cycle or triggering an extra annual fee.
- Codes must be chosen from Companies House’s condensed SIC list; using an ONS‑only code will cause the confirmation statement to be rejected.
- Directors should distinguish the company’s principal revenue‑generating activity from visible or subsidiary activities when deciding the primary SIC code.
- SIC codes should be reassessed at key trigger points such as business model shifts, new dominant revenue streams, or before finance and insurance applications.
What Is a SIC Code?
A SIC code is a five-digit number that describes a company’s principal economic activity. Companies House uses a condensed version of the Standard Industrial Classification 2007 framework, and every UK limited company must select at least one code from that list when it first registers. Up to four codes can be held simultaneously where the business operates across more than one sector.
The code is on the public register and visible to anyone who searches for the company. Banks, lenders, insurers, credit reference agencies, and investors use it as a basic data point when assessing a company’s profile. It is also used by HMRC and the Office for National Statistics for statistical and tax purposes.
Examples of SIC codes are as follows:
| SIC code | Company status |
|---|---|
|
99999 |
Dormant company with no significant accounting transactions |
|
74990 |
Non-trading company that has not yet begun business |
|
68100–68320 |
Property investment or buy-to-let company |
|
64202 |
Holding company with trading subsidiaries |
|
62000–63990 |
Technology, software, and IT services companies |
When Should You Update a SIC Code?
The SIC code should reflect the company’s current principal activity at all times. If the business has changed direction, expanded into a significantly different sector, or if the original code was selected in error at incorporation, the code should be corrected. A company that was set up for one purpose but has since shifted its focus should not continue to hold an outdated code simply because correcting it requires an administrative step.
Before applying for finance, insurance, or a grant, it is worth confirming that the registered code correctly reflects what the business does. These applications often use the registered code as a starting point, and an inaccurate entry can cause delays or rejection on grounds unrelated to the company’s actual eligibility.
Dormant companies require particular attention. A company with no significant accounting transactions should hold a code that reflects dormant status, typically 99999. When a dormant company begins to trade, the SIC code should be updated to reflect its actual activity at the next available opportunity.
How to Change a Company SIC Code at Companies House
The only way to change a company SIC code at Companies House is through the confirmation statement (form CS01). There is no standalone form or separate service dedicated to a SIC code update. The change must be made as part of a confirmation statement filing.
The confirmation statement is an annual filing obligation for all UK limited companies, including dormant ones. It confirms that the information on the register, including directors, Persons with Significant Control (PSCs), share capital, registered office, registered email address, and SIC codes, is accurate and up to date.
If a SIC code needs to be corrected urgently, a confirmation statement can be filed early at any point in the year. Filing early does not reset the 12-month period for the next required filing. The annual fee is payable only once per 12-month period, so early filing does not increase cost.
Choosing the Right SIC Code
Selecting the most appropriate SIC code requires care. The Companies House system is searchable by keyword, but the descriptions do not always map neatly to modern or specialist business models. A company should identify the code that most closely matches its principal activity, the activity from which it derives the majority of its income.
Where a business operates across multiple activities of broadly equal weight, up to four codes can be registered simultaneously. The primary SIC code should reflect the dominant revenue-generating activity, with secondary codes used to capture other significant areas. The most specific code available should be used in preference to a broad catch-all category.
The code entered must come from the Companies House condensed list, not the full ONS SIC 2007 framework. Not every ONS code appears on the Companies House version, and entering a code that exists in the ONS system but not on the Companies House list will result in a rejected filing.
Common Mistakes When Selecting or Changing SIC Codes
One of the most frequent errors occurs at the point of incorporation. Founders often select a SIC code based on what they expect the business to do, rather than what it is actually doing. Where trading has not yet begun, the choice is inevitably speculative, and the code may need to be reviewed as soon as the business settles into its principal activity.
Another common mistake is using the full ONS classification rather than the Companies House condensed list. The two frameworks share the same numbering system, but not all ONS codes appear on the Companies House list. Filing with an ONS code that Companies House does not recognise results in a rejected confirmation statement.
Directors also sometimes overlook the distinction between the company’s primary activity and its most visible one. A holding company that owns trading subsidiaries, for example, should generally hold a code reflecting its holding function, not the trading activity of its subsidiaries. Using the wrong type of code can create confusion for lenders and counterparties reviewing the register.
SIC Codes and Dormant Companies
A company is generally treated as dormant when it has had no significant accounting transactions during the relevant period. Companies House expects dormant companies to hold a SIC code that reflects that status. The standard code for a dormant company is 99999. A non-trading company that has not yet started business typically uses code 74990.
Using the wrong code for a dormant company is a common error made at the point of incorporation. Where a company is incorporated with a trading SIC code but never begins trading, the code should be reviewed and corrected at the next confirmation statement. When a dormant company does begin to trade, updating the SIC code is one of several steps required to bring the register up to date. The confirmation statement provides the appropriate mechanism for making that change, alongside any other updates that have become necessary since the last filing.
Changing SIC Codes and the Confirmation Statement Deadline
The confirmation statement must be filed at least once every 12 months. After the review period ends, directors have 14 days to submit the filing. Missing this deadline is a criminal offence for directors, and Companies House can begin strike-off proceedings against companies that repeatedly fail to comply.
If the plan is to update a SIC code at the next scheduled confirmation statement, it is worth checking how far away that date is. Where there is a pressing reason to correct the code, for example because a finance application is pending, filing an early confirmation statement is usually the more practical approach.
Updating a SIC Code After Incorporation
SIC codes are often chosen at incorporation based on what the founder expects the business to do. Early-stage businesses frequently evolve, and the original code may no longer be accurate within months of registration. The information required when setting up a UK company includes the initial SIC code, but that choice is rarely final.
The code should be reviewed at each key stage: when the business changes direction, when a new revenue stream becomes the primary one, or before applying for finance or contracts where the code will be scrutinised. A code that was accurate at incorporation can become misleading quickly as a business develops.
For those setting up a UK limited company, understanding from the outset that the SIC code will need periodic review, and knowing how to change it when necessary, avoids the problems that arise from leaving an outdated code in place.
Ongoing Compliance and SIC Code Management
For most companies, the SIC code is reviewed once a year as part of the confirmation statement process. Agents providing company secretarial services typically check the code for accuracy before each filing, flagging any discrepancies so they can be corrected as part of the same submission.
Where a company’s activities are genuinely diverse, reviewing whether the current selection of up to four codes still reflects the business accurately is a worthwhile exercise. As the business grows, the relative importance of different revenue streams can shift, meaning the primary code may need to change even where secondary codes remain appropriate.
The confirmation statement service covers the full preparation and filing process, including a SIC code review at each annual filing. Where the code needs to change, the update is included as part of the same submission rather than requiring a separate process.
Final Words
Keeping a company SIC code accurate is part of the wider obligation to maintain an up-to-date public register. Directors should treat SIC code accuracy as part of routine compliance housekeeping rather than a one-off task completed at incorporation and forgotten.
