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Step 1: Understand the two registrations
Forming a company at Companies House and registering it for corporation tax with HMRC are different things. HMRC is usually notified automatically on incorporation and issues a Unique Taxpayer Reference (UTR), but you must still tell HMRC when the company becomes active — starts trading — within three months.
Step 2: Gather what you need
Have your company registration number, the date you started trading, your main business activity, your accounting reference date, and details of directors to hand. Getting the trading start date right matters, because it sets your first accounting period and payment deadline.
Step 3: Register online
Register through HMRC's online service using your Government Gateway account. You will confirm when the company started trading and its accounting period. HMRC then sets the deadline for your first return and payment — nine months and a day after the period ends to pay, twelve months to file.
Step 4: Set up for filing and payment
Note your deadlines immediately, and plan how you will file the CT600 — accounting software or an accountant. Under Making Tax Digital the record-keeping expectations are rising.
Step 5: Start reserving for the bill
From your first profitable month, set money aside so the first bill is funded — see how to budget for corporation tax. If growth outpaces your reserve, finance bridges the gap.
Credicorp lends to your company, not to you personally, and takes no personal guarantee. See indicative terms on business loans, or apply online in minutes.
Frequently asked questions
Do I register for corporation tax when I incorporate?
Not fully. Companies House usually notifies HMRC, which issues a UTR, but you must separately tell HMRC when the company becomes active (starts trading) within three months. Missing that step is a common early error.
What is a UTR?
A Unique Taxpayer Reference — a 10-digit number HMRC uses to identify your company for corporation tax. You need it to file returns and make payments, and it is issued after incorporation.
When is my first corporation tax return due?
Twelve months after the end of your first accounting period, with payment due nine months and one day after the period ends. HMRC confirms the exact dates when you register the active company.
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