What Is a SIC Code and How Do I Choose One? (2026)
Every UK company must have a SIC code, yet it’s one of the most commonly overlooked details on the entire Companies House register — until it causes a rejected mortgage application, a blocked business bank account, or a flagged Confirmation Statement. This guide from Filing Accounts UK explains exactly what a SIC code is, how to choose the right one, and why keeping it accurate now matters more than ever, using only verified facts from official Companies House guidance.
At Filing Accounts, we help UK companies choose and update SIC codes correctly as part of company formation and Confirmation Statement filing. Official guidance is available at GOV.UK: Standard Industrial Classification of Economic Activities (SIC).
What Is a SIC Code?
A SIC (Standard Industrial Classification) code is a 5-digit number that Companies House and the Office for National Statistics (ONS) use to classify what your business actually does. Every company must provide at least one SIC code when it’s incorporated, and it appears publicly on your company’s overview page on the Companies House register. SIC codes exist purely for statistical and classification purposes — they help government track industry trends and the composition of the UK economy. Importantly, a SIC code is not a licence: choosing “management consultancy” today doesn’t legally stop you selling a completely different product next year.
Why Your SIC Code Matters More Than It Looks
Although it’s just a statistical label at heart, your SIC code quietly feeds into several real-world checks:
- Business bank account and payment provider checks — some providers flag or query accounts where the SIC code doesn’t match the business’s actual activity
- Mortgage and lending decisions — particularly for property companies. Using the wrong buy-to-let code, for example, can create complications with lenders
- HMRC risk-profiling — including for R&D tax credit claims, where your declared industry can influence how a claim is assessed
- Investor and lender due diligence — anyone reviewing your company will see your SIC code as part of understanding whether you’re a good fit for finance or investment
A mismatched SIC code won’t invalidate your company, but it can genuinely slow down or complicate things elsewhere.
How to Choose the Right SIC Code
Step 1: Use the Companies House Condensed List Only
Companies House uses a condensed version of the full ONS SIC classification — not every ONS code appears on it. You must search and select from the official Companies House condensed SIC code list; entering a code that only exists on the full ONS list will cause your filing to be rejected.
Step 2: Search by Keyword
Write your main business activity down in plain words — for example, “freelance graphic design” — then search the condensed list using a keyword from that description, such as “design.” The list is organised into 21 main industry categories, each containing more specific trade activities underneath.
Step 3: Check How Similar Companies Are Classified
If you’re not sure which code fits, search the Companies House public register for similar businesses and see which SIC code they’ve used. This is particularly useful where your business doesn’t map neatly onto an obvious category.
Step 4: Avoid Vague, Catch-All Codes Where a Precise One Exists
Codes like 74990 (“non-trading company”) or 82990 (“other business support service activities not elsewhere classified”) should only be used when nothing more specific applies. If a precise code exists for your actual trade, use that instead — vague codes are more likely to raise questions with lenders or during due diligence.
Step 5: Add Up to Three More Codes If Needed
You can select up to 4 SIC codes in total. If your company genuinely carries out more than one significant business activity, list your main revenue-generating activity first, followed by up to three additional codes for other significant activities.
Common SIC Code Mistakes for Specific Business Types
| Business Type | Common Mistake |
|---|---|
| Buy-to-let property | Using 68100 (buying/selling own property) instead of the more accurate 68209 (letting/operating own or leased property) — the wrong code can complicate mortgage applications |
| Online retailers / e-commerce | Not using 47910 (retail sale via mail order or internet), which some payment providers specifically look for |
| Dormant or non-trading companies | Leaving a dormant code (99999) or non-trading code (74990) in place after the company starts actively trading |
How to Change Your SIC Code
You change your SIC code by filing a Confirmation Statement (CS01) — there’s no separate form or additional fee just for a SIC code change. Within the Confirmation Statement, you can add, remove, or replace codes as needed, then submit and pay as normal.
- At your normal filing date: Update your SIC code as part of your regular annual Confirmation Statement, at no extra cost.
- Early, if needed urgently: If your business activity has already changed and you don’t want to wait for your normal date, you can file a Confirmation Statement early. This resets your 12-month review period, so check your current due date first.
- Fee: The standard £50 online Confirmation Statement fee covers your SIC code update — one filing fee covers the whole 12-month period, however many times you update within it.
For the full process and current fees, see our Confirmation Statement Hub.
Why You Can No Longer Just “Set and Forget” Your SIC Code
Under the Economic Crime and Corporate Transparency Act (ECCTA), Companies House now has stronger powers to challenge, reject, or remove information on the register that appears incorrect, inconsistent, or misleading — and this applies to SIC codes just as much as any other filed detail. One of the most common discrepancies Companies House sees is a company that’s actively trading but still showing a dormant (99999) or non-trading (74990) code from formation. If your SIC code doesn’t reflect your actual activity, you may experience filing rejections or delays while the discrepancy is investigated.
It’s worth reviewing your SIC code at every Confirmation Statement, asking: Are we actively trading, and does the code reflect that? Has our business activity changed or expanded into a new area since the code was last set?
A Note on SIC 2026
The ONS published an updated classification system, SIC 2026, in April 2026, introducing new codes for areas such as digital platforms, e-commerce, and green energy, and retiring a small number of outdated ones. As of now, Companies House has not set a mandatory adoption date, so companies should continue filing using the existing SIC 2007-based condensed list until an official transition date is announced. It’s sensible to be aware this change is coming, but no action is required yet.
SIC Codes at a Glance
| Item | Detail |
|---|---|
| Format | 5-digit number |
| Minimum required | 1 code |
| Maximum allowed | 4 codes |
| Where to choose from | Companies House condensed SIC list (not the full ONS list) |
| How to change it | File a Confirmation Statement (CS01) |
| Extra fee to change SIC code? | No — covered by the standard £50 CS01 fee |
| Dormant company code | 99999 |
| Non-trading company code | 74990 |
Common Mistakes to Avoid
Using a Code From the Full ONS List Instead of the Condensed List
Only codes on the Companies House condensed list are accepted — using an ONS-only code will get your filing rejected.
Leaving a Dormant or Non-Trading Code in Place After Trading Begins
This is one of the most common discrepancies Companies House flags, and can now trigger scrutiny under ECCTA.
Defaulting to a Vague, Catch-All Code
If a more specific code accurately describes your activity, use it — generic codes can raise more questions than they answer with lenders and investors.
Using the Wrong Property Code
Buy-to-let companies in particular should check they’re using 68209 rather than 68100, since the wrong code can complicate mortgage applications.
Never Reviewing It After Formation
Treat your SIC code as something to check at every Confirmation Statement, not something you set once and forget.
Frequently Asked Questions
How many SIC codes can my company have?
Up to 4. Most companies only need 1 or 2.
Does my SIC code legally restrict what my business can do?
No. It’s a statistical classification, not a licence — you can trade in a different area to your SIC code without breaking any rule, though it’s best practice to keep it updated.
How do I change my SIC code?
By filing a Confirmation Statement (CS01), either at your normal annual date or early if you need to update it sooner.
Is there a fee just to change a SIC code?
No separate fee — it’s covered by the standard £50 online Confirmation Statement fee.
What SIC code should a dormant company use?
99999. Once the company starts actively trading, this should be updated to reflect the real business activity.
Can Companies House reject my SIC code?
Yes. Under ECCTA, Companies House can challenge, reject, or remove SIC codes and other information that appears incorrect, inconsistent, or misleading.
Do I need to switch to SIC 2026 now?
No. SIC 2026 has been published but Companies House has not yet set a mandatory adoption date — continue using the current condensed SIC list for now.
Get Your SIC Code and Confirmation Statement Right — Talk to Filing Accounts UK
Choosing the right SIC code, and keeping it accurate as your business grows, is a small detail that can cause real friction with banks, lenders, and Companies House if it’s overlooked. At Filing Accounts, we help UK companies choose the correct SIC code and keep it updated as part of our Confirmation Statement filing service.
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