By
August 23, 2026
How Do I Register for Corporation Tax in the UK?
A UK limited company is usually set up for Corporation Tax when it is registered with Companies House. If it is not, you can add Corporation Tax services to the company's HMRC business tax account once the company starts doing business.
If your company becomes active and is within the charge to Corporation Tax, HMRC says you must tell them within 3 months of the start of your tax accounting period.
Corporation Tax becomes relevant when your limited company starts doing business.
HMRC considers activities such as the following as signs that a company has started doing business:
If your company is not carrying on business, it will usually be considered dormant for Corporation Tax.
It often is.
When you register a new limited company online through Companies House, you will usually be set up for Corporation Tax at the same time, unless the company is dormant.
If Corporation Tax was not set up when the company was incorporated—for example, because you registered through an agent, by post or using certain third-party software—you may need to add Corporation Tax services separately to your HMRC business tax account.
To add Corporation Tax services to your business tax account, you will generally need:
Your UTR is an important reference used by HMRC to identify your company for tax purposes.
A Unique Taxpayer Reference (UTR) is a 10-digit number issued by HMRC.
You can find your company's UTR on correspondence from HMRC.
If you have not received the company's UTR within 15 working days after registering the company, HMRC provides an online service for requesting it.
Make sure your company's registered office address is correct because HMRC correspondence is sent there.
If your company was not already set up for Corporation Tax, you can use your HMRC business tax account.
The basic process is:
HMRC guidance for adding Corporation Tax services
HMRC will send information needed to activate and manage the Corporation Tax service.
According to current HMRC guidance, the Corporation Tax activation code normally arrives within 10 days, or 21 days if you live abroad. It is sent by post to the company's registered office.
Once activated, you can use HMRC's online services to manage the company's Corporation Tax affairs.
If your company has not started doing business, it will usually be considered dormant for Corporation Tax.
A dormant company generally does not have Corporation Tax to pay because it is not generating taxable profits.
However, Companies House filing requirements can still apply even when a company is dormant.
When the company later starts trading or carrying on business, you may need to tell HMRC that it has become active.
Yes, potentially.
Being active for Corporation Tax purposes does not depend on whether the company ultimately makes a profit.
Once a company is active and HMRC requires a Company Tax Return, it may still need to file the return even if it makes a loss or has no Corporation Tax to pay.
Registering for Corporation Tax does not mean you immediately have tax to pay.
For most companies, Corporation Tax is normally due 9 months and 1 day after the end of the relevant accounting period.
The Company Tax Return normally has a separate deadline of 12 months after the end of the accounting period.
If your company becomes active and falls within Corporation Tax, HMRC says you must notify them within 3 months of starting your tax accounting period.
A new company will usually be set up for Corporation Tax when it is registered with Companies House. If it was not, Corporation Tax services can subsequently be added through the company's HMRC business tax account.
If you need to add Corporation Tax services to your business tax account, HMRC lists the company's 10-digit UTR among the information required.
A company that is not doing business is usually dormant for Corporation Tax. The position changes when it starts carrying on business.
Yes. HMRC provides online services for managing Corporation Tax and notifying HMRC when a company becomes active.
For many UK limited companies, Corporation Tax setup happens as part of the company registration process.
If it was not set up at incorporation, you can add Corporation Tax services to the company's HMRC business tax account once the business becomes active.
The key information to have available includes your company number, UTR, trading start date and accounting dates. You should also ensure the registered office address is correct so important HMRC correspondence and activation information reaches the company.
