When does a new limited company need to register for Corporation Tax?

Last updated · General guidance, not legal or tax advice

A new limited company must register for Corporation Tax within three months of starting to do business. "Doing business" includes buying, selling, advertising, renting property, employing someone or receiving income such as interest — not just making your first sale.

A company that has been registered but is not yet doing anything may be dormant for Corporation Tax purposes. You still need to tell HMRC the right status, so check the current GOV.UK guidance rather than waiting.

What counts as starting to do business?

According to HMRC guidance, examples of activity that can mean a company is active include:

  • Buying or selling goods or services
  • Advertising or marketing
  • Renting an office or other property
  • Employing someone
  • Receiving income, such as bank interest

Activity starts the company's first accounting period for Corporation Tax. See GOV.UK: set up your company for Corporation Tax.

What is a dormant company?

A company is usually dormant for Corporation Tax if it is not doing business and has no other income. Even a dormant company must still file annual accounts and confirmation statements with Companies House. If HMRC writes to the company about Corporation Tax, it should reply to confirm the dormant status. See GOV.UK: dormant companies.

What is the company's UTR?

After incorporation, HMRC normally sends the company a Unique Taxpayer Reference (UTR) by post to the registered office address. You will need it to register for Corporation Tax and deal with HMRC online. If your registered office is a service address, make sure official post is passed on promptly — with our registered office service, official HMRC post is scanned and sent to you digitally.

How do I register?

You register online through HMRC, usually by setting up a business tax account for the company. You will need the company's registration number, UTR, the date it started business, and details such as its main activity. An accountant can register on the company's behalf.

What deadlines follow? (high level)

  • Registration — within three months of starting to do business
  • Paying Corporation Tax — for most smaller companies, nine months and one day after the end of the accounting period; larger companies pay in instalments
  • Company Tax Return — usually 12 months after the end of the accounting period

These are separate from Companies House deadlines. Check your exact dates on GOV.UK, and see annual filing deadlines for how they fit together.

Why it pays to get this right early

Missing registration or filing deadlines can lead to penalties and interest. Setting up Corporation Tax, bookkeeping and a calendar of key dates in the first few weeks avoids most problems. If you would rather not handle this yourself, speak to an accountant — In Front Accounting can register the company and manage its returns.

In short

A new UK limited company must register for Corporation Tax within three months of starting to do business. Doing business includes buying or selling, advertising, renting property, employing someone or receiving income such as interest — not just the first sale. A company that is not yet active may be dormant for Corporation Tax but must still file accounts and confirmation statements with Companies House. HMRC usually posts a Unique Taxpayer Reference (UTR) to the registered office after incorporation, which you need to register. For most smaller companies, Corporation Tax is due nine months and one day after the accounting period ends, and the Company Tax Return is due 12 months after. Confirm your exact dates on GOV.UK.

Frequently asked questions

Do I need to register if the company hasn't made any money yet?

Registration depends on starting to do business, not on making a profit. Advertising or buying supplies can count. Check GOV.UK for your situation.

What if I lose the UTR letter?

You can ask HMRC to resend it. Make sure official post sent to your registered office reaches you reliably.

Sources and official guidance

This guide is general information about UK rules as at 3 October 2026. It is not legal, tax or financial advice.