By
August 30, 2026
When Must a New UK Company Register for Corporation Tax?
A new UK limited company must generally register for Corporation Tax within three months of starting business activities.
The deadline does not necessarily run from the company’s incorporation date. If the company remains dormant after incorporation, it will usually register when it begins trading or receiving taxable income.
This distinction is important. Incorporating a company and starting business activity can happen on the same day, but they can also occur months apart.
A company must notify HM Revenue and Customs (HMRC) within three months of the beginning of its first Corporation Tax accounting period.
For most new companies, that accounting period begins when the company starts carrying on business activities.
In practical terms:
HMRC describes this obligation as notifying it that the company is within the charge to Corporation Tax. See the official Corporation Tax guidance.
Not always.
The incorporation date is the date on which Companies House legally creates the company. The Corporation Tax registration deadline is generally connected to the date the company becomes active.
Consider these examples:
A company is incorporated on 1 February and immediately begins supplying services to customers. Its Corporation Tax accounting period will normally begin on 1 February, and it should register by 1 May.
A company is incorporated on 1 February but does not begin business activities until 1 June. It will generally be dormant for Corporation Tax between February and June. Its three-month registration period would usually begin when it becomes active in June.
A company is incorporated to operate a retail business but receives interest or rental income before opening its shop. That income may bring it within the charge to Corporation Tax earlier than expected.
The company’s actual activities—not simply the date on its certificate of incorporation—determine when registration is required.
A company does not necessarily have to issue its first customer invoice before it becomes active.
HMRC’s examples of business activity include:
A company may therefore become active during its preparation or launch phase.
For example, paying for advertising, purchasing stock or taking on employees may indicate that the business has begun, even if no customer revenue has yet been received. HMRC provides further examples in its guidance on adding Corporation Tax services to a business tax account.
The treatment of pre-trading activity can depend on the circumstances.
Some preliminary actions, such as opening a bank account, issuing shares or paying incorporation costs, may not by themselves mean that the company has started trading. More substantial commercial activities—such as marketing, buying stock, employing staff or entering customer contracts—may indicate that it has.
The company should identify a reasonable and supportable start date based on what it actually did.
Keeping dated records of contracts, invoices, advertising campaigns, purchases and bank transactions can help demonstrate how the start date was determined. If the position is unclear, professional tax advice may be appropriate.
A newly incorporated company that has not started business activity is normally dormant for Corporation Tax.
It does not usually need to register as an active company until it begins trading or receives taxable income. However, HMRC may write to the company after incorporation. If HMRC asks for information or expects a tax return, the company should respond and confirm that it is dormant where appropriate.
Dormancy for Corporation Tax does not remove the company’s obligations to Companies House. A dormant company will normally still need to:
The company must notify HMRC when it becomes active. More information is available in HMRC’s guidance on dormant companies and Corporation Tax.
When forming a company online, the owner may be able to provide information for Corporation Tax at the same time.
However, the directors remain responsible for ensuring that HMRC has the correct details, including:
Directors should not assume that Corporation Tax registration has been completed merely because the company has been incorporated.
Companies House and HMRC perform different functions. Companies House creates and maintains the company’s public record, while HMRC administers its tax affairs.
A company can normally register by adding Corporation Tax services to its business tax account.
It will usually need:
HMRC normally sends the company’s Unique Taxpayer Reference, or UTR, to its registered office after incorporation. The letter should be retained securely because the UTR is used for the company’s tax affairs.
If the UTR has not arrived within the expected period, the company can use HMRC’s online service to request it. HMRC states that the letter normally arrives within approximately 15 working days after a request.
The company should enter the date on which it genuinely began carrying on business or receiving taxable income.
It should not automatically use:
Any of those dates might be relevant, but none is automatically the correct start date in every case.
The start date should reflect the company’s actual commercial activity. Supporting evidence might include its first sales contract, stock purchase, advertising invoice, property lease or employment record.
After registration, HMRC will use the company’s start date and accounting information to establish its Corporation Tax accounting period.
The company must then:
For most small companies, Corporation Tax must be paid nine months and one day after the end of the accounting period. The Company Tax Return is normally due 12 months after the accounting period ends.
These are separate deadlines. Paying the tax does not replace the obligation to submit the return, and submitting the return does not extend the payment deadline.
Yes.
A Corporation Tax accounting period cannot normally exceed 12 months. A company’s first statutory accounts may cover more than 12 months because the accounting period can run from incorporation to the end of the following month one year later.
If the first accounts cover more than 12 months and the company was active throughout that period, it may have to submit two Company Tax Returns:
This is a common source of confusion for new company directors. HMRC explains the interaction in its guidance on first company accounts and tax returns.
A company that misses the three-month notification deadline should register as soon as possible.
HMRC may charge a failure-to-notify penalty, particularly where the delay results in Corporation Tax remaining unpaid. The amount can depend on matters such as:
Registering late does not change the original accounting period or automatically extend the tax payment and filing deadlines.
If the company has traded for some time without registering, its directors should reconstruct the accounting records, identify the correct start date and consider obtaining advice from an accountant or tax adviser.
Usually, yes.
Registration depends on the company becoming active, not on whether it makes a profit.
A company that trades at a loss may still need to:
Subject to the applicable rules, a trading loss may potentially be carried forward or otherwise relieved against taxable profits. The absence of Corporation Tax to pay does not necessarily remove the registration and reporting obligations.
Generally, yes.
A UK-incorporated limited company is normally within the UK Corporation Tax system regardless of whether its directors or shareholders live overseas.
An overseas owner should ensure that:
The residence of the shareholder does not normally postpone the company’s Corporation Tax registration deadline.
When a new company is preparing to trade, its directors should:
Only if it becomes active at or shortly after incorporation. If it remains genuinely dormant, the three-month period will usually begin when it starts business activity.
Not necessarily. Opening an account alone may not amount to trading, although transactions through that account could provide evidence that the company has become active.
Not always. Advertising, purchasing stock, employing staff or other commercial activity may cause the company to become active before its first invoice is issued.
Yes, if it is active. The obligation is based on business activity rather than profitability.
Yes. An authorised accountant or tax agent can assist with registration and ongoing Corporation Tax compliance, but the directors remain legally responsible for the company meeting its obligations.
The company should not ignore it. It should contact HMRC, explain that the company is dormant and ask whether the notice can be withdrawn. If HMRC does not withdraw it, the company must comply with the notice.
A new UK company must normally register for Corporation Tax within three months of starting business activities or receiving taxable income.
The deadline is not automatically three months after incorporation. A company that remains dormant can generally wait until it becomes active, although it must continue meeting its Companies House obligations and respond to any correspondence from HMRC.
Because activities such as advertising, purchasing goods, employing staff or renting property can indicate that business has started, directors should establish the company’s start date carefully and retain evidence supporting it.
