How to register for Corporation Tax in UK? [Step-by-step Guide]

Setting up a limited company is only the first step - after that, you need to register for corporation tax. This ensures you're legally compliant and ready to file your annual CT600 form.

What is corporation tax?

Corporation tax is a tax on the profits your limited company makes, whether from trading, providing services, investments, or selling assets. UK companies pay this at the current main rate (19%–25%, depending on profit tiers).

When and why you must register for corporation tax?

You must register for corporation tax within 3 months of starting business activity - this includes first sales, advertising, hiring staff, or renting premises.
Why: Failing to register or filing late can lead to penalties - registering ensures HMRC sends your deadlines and avoids fines.

What is CT41G form?

A CT41G form (often received as a letter) is HMRC’s official notification to new limited companies, containing your Unique Taxpayer Reference (UTR) and guidance on registering for Corporation Tax.

It confirms your legal obligations, such as the company name, start of business, accounting period and trading address, and helps HMRC set up your tax profile.

CT41G is a document issued by HMRC and is issued to newly incorporated companies or those that have changed their status so that they can prove to HMRC that they are a UK resident company.

Within approximately three weeks of the new business being incorporated, HMRC will send you a letter which includes a CT41G form confirming your company’s unique tax reference number (UTR).

Make sure you keep UTR number safe as you will require it to complete your tax returns and to communicate with HMRC…

Step-by-step guide: How to register for corporation tax online

1. Incorporate your company - Use Companies House or a formation provider like ANNA for free company registration.

2. Receive your CT41G & UTR letter - Within ~2–3 weeks, HMRC sends your Unique Taxpayer Reference and the CT41G form to your registered office.

Note: If you have not received your company UTR letter within 2 months of registering your business, please contact HMRC as you have to register for Corporation Tax within 3 months of starting to do business.

3. Set up your Government Gateway - Log in or create an account to manage business taxes, including VAT, PAYE, and corporation tax registration.

4. Register the company - Provide HMRC with:

• The date your company accounts are made up to
• Company name & registration number
• Date trading began
• Accounting period & year-end
• Business activities and trading address.

5. Add Corporation Tax service - Under "Services you can add" in your HMRC business tax account, enroll in Corporation Tax; you'll receive an activation code to fully register.

6. Activation code delivery - HMRC typically takes up to 10 working days (or up to 21 days internationally) to send the code.

7. Access your account - Once you activate your service, your corporation tax account is live. You'll see your company’s accounting details and filing deadlines.

Where to start registering for Corporation Tax?

In order to register for Corporation Tax online you first need to sign in to the Government Gateway for your business. If you do not have a user ID, you can create one on the government website.

Once you’ve got a user ID and can access your Government Gateway, what’s next?

It is time to start considering the taxes your business will have to pay.

What taxes will your new business need to pay?

This will depend on a couple of factors, but all limited businesses pay Corporation Tax on their business profits at the end of their financial year.

Corporation Tax

All limited businesses must pay Corporation Tax; this is a tax on the businesses' taxable profits. Taxable profit is the money the business makes from doing business (known as trading profits), investments and the profits made from selling assets for more than they cost (chargeable gains).

Once you’ve been trading and you come to the end of your first financial year, you need to prepare:

• Your annual accounts
• A company tax return

You are required to file these with Companies House and HMRC within specific deadlines. Here’s a handy guide:

What if I am late filing my company tax return?

Being late with your filings can mean you receive penalties from HMRC. These are as follows:

Bear in mind that if your tax return is late 3 times in a row, each £100 penalty is increased to £500.

Don't forget to check! Your new business might also be eligible to pay additional taxes including:

• Value Added Tax (VAT)
• Employer National Insurance contributions
• Personal tax payments for limited company directors

Helpful tips & key considerations

• Dormant vs active: If your Ltd is not trading, you don’t need to register until it becomes active.
• Align accounting periods: Matching your company’s year‑end with the UK tax year (5 April) makes tax planning simpler.
• Record‑keeping: Keep accurate digital records (invoices, purchases, payroll, etc.) for at least six years.
• Other registrations: In addition to corporation tax, you'll likely need PAYE and VAT. ANNA can handle all of these seamlessly together.

To wrap up

Registering for corporation tax may feel overwhelming, but it’s simply a matter of following a few clear steps. Once you have your UTR and Government Gateway set up, you're ready to manage your taxes effectively. Tools like ANNA +Taxes can automate filing, reminders, and record-keeping to keep everything on track.

Thousands of UK entrepreneurs trust ANNA to kickstart and run their businesses. Wanna join them and optimize your business operations?

FAQ

What do I need to report to HMRC after registering the company?

You will need to provide HMRC with the following information on the CT41G form relating to the trading activities of your business:

• The date your company accounts are made up to
• Your full company name and registration number
• The date your business started trading
• The main trading address where day-to-day business is carried out
• The type of business activities carried out

How long does it take to register for Corporation tax in UK?

• Incorporation: online in minutes; paper filings can take 5 working days.
• UTR/CT41G letter: arrives in ~2–3 weeks.
• Activation codes: dispatched within 7–21 working days 
• Full registration for corporation tax: typically completed in under a month after starting trading.