Register for Self Assessment
When and how to register for Self Assessment tax.
Corporation Tax
Register your company for Corporation Tax
Step-by-step Corporation Tax registration for new companies.
UK-wide
Guide summary
Register your company for Corporation Tax within 3 months of starting business activity. You need your company’s Unique Taxpayer Reference (UTR) from HMRC, business start date, and accounting details. After registering, file a tax return annually and pay what you owe by the deadline.
- Register with HMRC within 3 months of starting business activity
- You will need your company’s 10-digit UTR from HMRC
- Register online using your Government Gateway account
- Choose your accounting period end date (usually 12 months)
- Activate your HMRC online account with a posted code
- File your CT600 tax return within 12 months of year-end
- Pay Corporation Tax 9 months and 1 day after year-end
- Main tax rate is 25% on profits over £250,000
- Small profits rate is 19% on profits up to £50,000
- Late registration may lead to late filing penalties
On this page
UK-wide
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Who must register
All UK limited companies must register for Corporation Tax with HMRC. You must do this within 3 months of starting any business activity, including buying, selling, advertising, renting a property, or employing someone.
A newly incorporated company that has not yet started trading does not need to register immediately, but must register as soon as it begins any taxable activity.
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1
Gather your information
You will need: your company's Unique Taxpayer Reference (UTR) from HMRC, date of incorporation, date you started or intend to start business activity, your company's registered office address, the nature of your business, and your accounting period end date.
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2
Register online with HMRC
Use your Government Gateway account to register for Corporation Tax. If your company was incorporated at Companies House, HMRC will have already sent a UTR by post within about 2 weeks of incorporation.
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3
Confirm your accounting period
Choose your accounting period end date. Most companies use 31 March (aligning with the tax year) or their incorporation anniversary. This determines your CT600 filing and payment deadlines.
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4
Set up your HMRC online account
Once registered, activate your Corporation Tax online service to file returns and view your account. You will need the activation code HMRC sends by post, which takes 7-10 working days.
What happens after registration
After registration, HMRC will confirm your Corporation Tax reference and accounting period. You will receive a notice to deliver a Company Tax Return (CT600) shortly after your first accounting period ends.
Late registration
There is no specific penalty for late Corporation Tax registration. However, if you file your CT600 late or pay Corporation Tax late because you were not registered, the normal late filing penalties and late payment interest apply. Registering promptly avoids these risks.