Corporation Tax Deadlines

Corporation Tax isn’t the exciting part of running your own business, but missing the deadlines can be costly!

If your business is liable for making Corporation Tax payments, it’s vital that you fully understand when the key deadlines are and the risk of making late payments to HMRC.

In this blog, we break down the key deadlines you need to know, how they work and what you can do to stay ahead of HMRC

Corporation Tax at a glance

Corporation Tax is a direct tax that a company must pay to HMRC on its profits. This includes profits from:

Trading
Investments
Gains on the sale of assets (chargeable gains)

UK Corporation Tax is primarily paid by:

UK Limited Companies
Foreign companies with a UK branch or office
Clubs, Co-operatives and other unincorporated associations (like community or sports groups)

Read more: CT600 Forms

Why are Corporation Tax deadlines important to understand?

Understanding the corporation tax deadlines helps you:

Stay legally compliant
Avoid penalties and interest
Plan your finances and manage cash flow more effectively

Missing deadlines can quickly become expensive, especially if errors go unnoticed.

When are the Corporation Tax deadlines?

There are two key deadlines you need to be aware of for corporation tax.

1. Corporation Tax Return Submission Deadline

This is when you tell HMRC how much Corporation Tax you owe.

Due 12 months after the end of your accounting period.

Example

If your accounting period ends on 31st March 2024, you need to submit by 31st March 2025.

2. Corporation Tax Return Payment Deadline

This is when the tax itself must be paid.

Due 9 months and 1 day after the end of your accounting period

Example

If your accounting period ends on 31 March 2024, the payment of corporation tax is due 1st January 2025.

Quarterly Instalment payments (QIPs)

Companies that are considered ‘large or very large’ must pay their corporation tax in Quarterly Instalment Payments (QIP’s). The limits for falling into these categories are:

Large Companies: Profits greater than £1.5 million
Very large: Profits greater than £20 million

These limits are also further reduced for any associated companies during the period.

For example, a small UK subsidiary of a global group of 100 companies will have smaller limits, so it’s important to check with your accountant to see if you’ll be affected.

When do I need to register for Corporation Tax?

You must register for Corporation Tax within three months of your company becoming active.

A company is considered “active” for Corporation Tax purposes when it starts doing any of the following:

Buying or selling goods
Advertising your products or services
Renting a property for business operations
Employing staff
Earning interest from investments or receiving other income

How do I register for Corporation Tax?

Incorporating your business by registering as a limited company on Companies House, automatically ‘registers’ you for Corporation Tax. HMRC will then send a letter to your registered office containing your Unique Taxpayer Reference (UTR) – this is important as you can’t submit your corporation tax returns without it.

Once you receive your UTR, you can add the Corporation Tax services to your HMRC business tax account. Your agent will also need this for the 64-8 agent authorisation process to enable them to speak to HMRC on your behalf.

Important considerations when registering for Corporation Tax

Failing to register within the three-month window can result in penalties from HMRC.
If your company is dormant (i.e. not doing business), you do not need to register for Corporation Tax until it becomes active.
You must, however, still file dormant accounts with Companies House.