Home / Guides / How to Register a Limited Company for Corporation Tax
Last updated 23 October 2026. Written by the Limited Company Accountant UK team, part of Accotax. Figures are for the 2026/27 tax year; always check GOV.UK for the latest rates.
Short answer: You must register for Corporation Tax within three months of starting to trade or doing other business. Register online with HMRC using your Companies House number and Unique Taxpayer Reference.
At a glance
| Deadline | Within 3 months of starting business |
|---|---|
| Where | HMRC online |
| You need | Company number, UTR, start date |
| Then | File CT600 and pay on time |
Step by step
- Create or sign in to a Government Gateway account for the company.
- Enter your company details and accounting period.
- Receive your UTR by post to the registered office.
- Activate the Corporation Tax service with the code in the letter.
What to do next
Diary your payment date, which is nine months and one day after your year end, and your CT600 filing date, which is 12 months after your year end.
Want this handled for you?
Fixed monthly fee, named accountant, free first consultation. Get a free quote or call 0203 4411 258.
Penalties
Failing to notify HMRC can lead to penalties, so register early if you are unsure whether you have started trading.
The bottom line
You must register for Corporation Tax within three months of starting to trade or doing other business. If you would rather not do it alone, our fixed fees start at £45.83 + VAT a month.
Frequently asked questions
Does a dormant company need to register?
Not until it starts to trade or receives income, but check with an adviser.
Does Companies House tell HMRC?
HMRC is told about new companies, but you still need to set up the Corporation Tax service.
Ready for a fixed monthly price?
Our packages start at £45.83 + VAT and cover accounts, tax and deadlines. Get a free quote or call 0203 4411 258.
Keep reading