Updating Your SIC Code at Companies House

At Towerstone Accountants we provide specialist limited company accountancy services for directors and owner managed businesses across the UK. We created this webpage for people responsible for company filings and statutory records who want clear guidance on Companies House requirements without jargon. Our aim is to help you understand your obligations, avoid filing errors, and stay compliant with Companies House and HMRC.

Changing a SIC code at Companies House is a task that sounds more complicated than it really is, yet it often causes unnecessary worry for directors. I am regularly asked whether changing a SIC code will trigger scrutiny, affect tax, or cause problems with banks or HMRC. In most cases, the answer is no, provided it is done correctly and reflects what the company actually does.

In this guide I will explain what a SIC code is, why it matters, when it should be changed, and exactly how to change it at Companies House. I will also cover the common mistakes I see, how SIC codes interact with tax and compliance, and how to choose the right code when a business evolves. Everything here is based on UK practice and how the process works in the real world.

What a SIC code is

A SIC code is a Standard Industrial Classification code. It is a numerical code used to describe the main business activities of a company.

In the UK, companies are required to select at least one SIC code when they are incorporated and to keep that information up to date. The code helps government bodies understand what types of activities companies are engaged in across the economy.

SIC codes are recorded and displayed publicly at Companies House.

In simple terms, a SIC code is a classification label. It is not a licence, approval, or permission to trade.

Why SIC codes exist

SIC codes exist primarily for statistical and administrative purposes.

They are used to:

• Analyse economic activity

• Group similar businesses together

• Support government research and reporting

• Help some regulators identify relevant sectors

They are not used to determine tax rates or permissions, although they may influence how some bodies view your business at a high level.

Why companies need to change their SIC code

Many companies outgrow or move away from their original SIC code.

This is completely normal. Businesses evolve, pivot, add services, or change focus over time.

Common reasons I see for changing a SIC code include:

• The company has moved into a new line of business

• The original SIC code was selected incorrectly at incorporation

• The company now has multiple activities

• The business has become more specialised

• A bank or adviser has highlighted a mismatch

There is no penalty for changing a SIC code, provided the new code is accurate.

When you should change your SIC code

You should change your SIC code when the current code no longer reflects the company’s main activity.

This does not mean you need to change it for minor or occasional activities. The focus should be on what the company mainly does.

I usually advise clients to ask:

• What generates most of the turnover

• What activity best describes the business today

• What an external party would reasonably say the business does

If the answer differs from the existing SIC code, it is time to update it.

Does changing a SIC code affect tax

This is one of the biggest concerns directors raise.

Changing a SIC code does not directly change how tax is calculated or paid.

Corporation Tax, VAT, PAYE, and other taxes are determined by what the company actually does, not by the SIC code itself. HMRC focuses on real activity and transactions, not classification labels.

Tax is overseen by HMRC and is based on substance rather than description.

That said, having an accurate SIC code helps avoid confusion and questions later.

Does changing a SIC code trigger checks

In my experience, changing a SIC code does not automatically trigger checks or investigations.

Companies change SIC codes every day for legitimate reasons. It is a normal administrative update.

Problems tend to arise only where:

• The SIC code change contradicts other filings

• The company claims reliefs inconsistent with its activity

• The business activity itself raises regulatory issues

Accuracy and consistency are what matter.

How many SIC codes a company can have

A UK company can have up to four SIC codes recorded at Companies House.

This is useful for businesses with more than one significant activity.

For example, a company might:

• Trade in one area

• Provide consultancy in another

• Hold investments alongside trading

In these cases, multiple SIC codes can give a more accurate picture.

However, the first listed SIC code should usually reflect the main activity.

Where SIC codes are recorded

SIC codes are recorded as part of the company’s public record at Companies House.

They appear on:

• The company profile page

• The confirmation statement

• Some public data feeds

They are not usually included in statutory accounts themselves.

How to change your SIC code at Companies House

Changing your SIC code is straightforward and can be done online.

There are two main ways to update it:

• Through the confirmation statement

• By filing an early update online

The most common and simplest method is via the confirmation statement.

Changing SIC code via the confirmation statement

The confirmation statement is an annual filing that confirms company details are up to date.

When filing the confirmation statement, you are given the opportunity to:

• Review existing SIC codes

• Remove incorrect codes

• Add new codes

This update takes effect as soon as the confirmation statement is filed and accepted.

For many companies, this is the natural point at which SIC codes are reviewed and corrected.

Changing SIC code outside the confirmation statement

If you need to change your SIC code urgently, you do not have to wait for the confirmation statement.

You can update SIC codes online using the Companies House service at any time.

This is useful where:

• The business has changed activity mid year

• A bank or supplier requires an updated record

• An error needs correcting quickly

The update is usually processed immediately.

Step by step process to change SIC code online

In practical terms, the process is as follows:

• Sign in to the Companies House online service

• Select the company you want to update

• Choose the option to update company details

• Navigate to the SIC code section

• Remove or amend existing codes

• Add the correct SIC code or codes

• Submit the update

There is no fee for changing a SIC code.

Choosing the correct SIC code

Selecting the right SIC code is important, but it does not need to be perfect to the last detail.

SIC codes are broad categories, not bespoke descriptions.

When choosing a code, I advise:

• Focus on the closest match to main activity

• Avoid overthinking minor differences

• Use multiple codes where genuinely needed

• Be consistent with how the business presents itself elsewhere

Companies House provides a searchable list of SIC codes, which makes selection easier.

Common mistakes when choosing SIC codes

The most common mistakes I see include:

• Selecting a code that is too broad or too vague

• Keeping an old code that no longer applies

• Using a code because it sounds good rather than accurate

• Forgetting to update codes after a pivot

• Listing too many codes without justification

Accuracy matters more than appearance.

SIC codes and banking relationships

Some banks and lenders look at SIC codes when assessing applications.

This is usually for initial categorisation rather than detailed analysis.

If your SIC code does not match what you tell the bank you do, it can cause delays or questions.

Keeping SIC codes aligned with reality helps avoid friction in these situations.

SIC codes and insurance

Insurance providers may also reference SIC codes when underwriting policies.

An incorrect SIC code can result in:

• Incorrect cover

• Invalidated policies

• Disputes during claims

This is another reason why accuracy matters beyond pure compliance.

SIC codes and VAT registration

VAT registration is not determined by SIC codes, but mismatches can cause questions.

For example, if a company is VAT registered for construction services but has a SIC code for retail, HMRC may seek clarification.

Again, substance matters more than labels, but consistency helps.

What happens if you do not update your SIC code

Failing to update a SIC code is rarely treated as a serious offence, but it can cause practical issues.

These include:

• Confusion for third parties

• Inaccurate public records

• Delays with banks or insurers

• Questions during due diligence

Updating a SIC code is quick and free, so there is little reason not to keep it accurate.

SIC codes and company accounts

SIC codes do not usually appear in filed accounts, but they influence how companies are categorised in databases and reports.

During company sales or investment discussions, discrepancies are often spotted and queried.

Cleaning up SIC codes early avoids unnecessary questions later.

How often SIC codes should be reviewed

I recommend reviewing SIC codes at least once a year.

The confirmation statement is a natural reminder, but you should also review them when:

• Launching a new service

• Dropping an old activity

• Rebranding or repositioning

• Preparing for finance or sale

Regular review keeps records tidy and accurate.

Using multiple SIC codes correctly

Multiple SIC codes should be used where the company genuinely has more than one material activity.

However, avoid using multiple codes simply to cover every possibility.

In my experience, two or three well chosen codes are usually sufficient.

Who is responsible for SIC codes

Responsibility for SIC codes sits with the company directors.

Although accountants and company secretarial services often assist, directors are ultimately responsible for ensuring information filed at Companies House is accurate.

This responsibility comes from company law and sits alongside other filing obligations.

How accountants help with SIC code changes

An accountant often helps by:

• Reviewing current activities

• Identifying appropriate SIC codes

• Ensuring consistency with tax filings

• Updating records where authorised

This is particularly useful for companies with complex or evolving activities.

Common myths about SIC codes

There are a few myths I hear repeatedly.

These include:

• Changing a SIC code changes tax rates

• SIC codes must be changed every time turnover shifts

• You can only choose one SIC code

• Using the wrong code is illegal

None of these are true when understood properly.

SIC codes and regulatory sectors

Some sectors are regulated, such as financial services or healthcare.

In these cases, the SIC code does not grant permission to operate. Separate regulatory approval is still required.

The SIC code is descriptive, not authorising.

Final thoughts

Changing a SIC code on Companies House is a simple but important housekeeping task. It does not affect tax directly, does not attract automatic scrutiny, and does not change what a company is allowed to do.

What it does is ensure the public record reflects reality. That accuracy helps with banks, insurers, advisers, and anyone carrying out checks on the company.

In my experience, companies that keep their SIC codes up to date tend to have fewer administrative issues and smoother interactions with third parties. It is a small task that removes unnecessary friction and helps keep the company’s records clean and credible.

You may also find our guidance on what is companies house and companies act 2006 helpful when dealing with related Companies House tasks. For a broader overview of filings, registers, and statutory duties, you can visit our companies house hub.