Important Guidance

Charity Trustees Have Received a Letter From HMRC to File a Corporation Tax Return – What Shall We Do?

A complete guide for UK charity trustees on understanding and responding to HMRC Corporation Tax Return notices (CT603)

Last updated: May 2026 12 min read Corporation Tax

What Does the HMRC Letter Look Like?

When HMRC sends a Corporation Tax notice to a charity, you will receive a letter titled "Corporation Tax Notice to Deliver a Corporation Tax Return" (commonly known as a CT603 notice). This official document requests your charity to file a CT600 Corporation Tax return by a specific deadline.

HMRC Corporation Tax Notice to Deliver a Company Tax Return CT603 form for charities with filing deadline of 5 June 2025 - official HMRC letter example showing how the CT603 notice looks

Example of an HMRC Corporation Tax notice showing the filing deadline

Important: The letter will clearly state the filing deadline. Missing this deadline can result in penalties even if no Corporation Tax is due.

Why Has HMRC Sent This Letter to Our Charity?

There are several common reasons why HMRC may issue a CT603 notice to a charity.

1. Registered as a Company

Many charities are registered as charitable companies with Companies House. HMRC's systems may automatically issue Corporation Tax notices to all companies.

2. Review Activities

HMRC may want confirmation that the charity has no taxable income, qualifies for tax exemptions, and applies income for charitable purposes.

3. Known Trading Income

HMRC may issue notices where they believe the charity has trading income, commercial activities, property income, or investment income.

4. System Generated

Notices are sometimes automatically generated even where no Corporation Tax is payable. This is common for newly incorporated charities.

Key point: Receiving this letter does not automatically mean the charity owes Corporation Tax. Most UK charities benefit from Corporation Tax exemptions.

What Should Trustees Do After Receiving the HMRC Letter?

There are usually several options available when your charity receives a CT603 notice.

1 File the Corporation Tax Return CT600

The safest option in many cases is to submit the CT600 return before the deadline, particularly where:

  • HMRC confirms the notice remains active
  • The charity has trading income
  • The charity has taxable income or gains
  • Trustees are unsure about the charity's tax position

From 01/04/2026: Most charity Corporation Tax returns must be filed electronically using commercial software. There is no longer a free HMRC online filing service. Read HMRC filing guidance

2 Call HMRC Corporation Tax or Charity Helpline

Trustees can contact HMRC directly and explain the charity's situation. This may help where the charity has no taxable income, is fully exempt, or the notice may have been issued in error.

HMRC Charity Helpline

Telephone: 0300 123 1073

Monday to Friday, 8:30am to 5pm excluding bank holidays

Find HMRC Corporation Tax contact details

3 Write to HMRC and Ask Them to Remove the Notice

In many cases, charities write to HMRC explaining the organisation is a registered charity with no taxable income, and all income is used for charitable purposes.

If HMRC formally removes the notice, the charity normally does not need to file the CT600 return. However, if HMRC refuses to remove the notice, the charity will usually still need to file by the deadline.

Warning: Trustees sometimes assume they do not need to file simply because no tax is due. Unfortunately, HMRC penalties can still apply even where the charity owes no tax.

What Happens if the Charity Ignores the HMRC Letter?

Ignoring the CT603 notice can create serious problems. Even where no Corporation Tax is payable, HMRC may still issue consequences.

Late Filing Penalties

Financial penalties that increase over time

Warning Letters

Further notices and escalating communications

Interest Charges

Where tax is eventually found to be due

Escalating Penalties

For repeated failures to comply

HMRC expects charities to either file the CT600 return or contact HMRC and resolve the notice formally. Simply ignoring the letter is rarely a good idea.

Read HMRC Corporation Tax penalties guidance

FAQ

Frequently Asked Questions

Practical Advice for Charity Trustees

If your charity receives a CT603 notice, follow these steps:

Do Not Ignore the Letter

Ignoring the notice may lead to penalties even where no tax is payable.

Check the Filing Deadline Carefully

The notice normally states the filing deadline clearly.

Review the Charity's Income Sources

Consider whether the charity has trading income, rental income, investment income, or taxable gains.

Contact HMRC Early if Unsure

HMRC charity teams can often clarify whether a return is required. Read HMRC charity tax guidance

Seek Professional Advice if Needed

Charity tax rules can become complicated, especially where charities undertake trading or commercial activities. Contact our team for help.

Final Thoughts

Receiving an HMRC Corporation Tax return notice can feel stressful for charity trustees, especially for small volunteer run organisations. However, in many cases the charity may not actually owe Corporation Tax.

The key point is this: Do not ignore the letter.

Trustees should either file the CT600 return by the deadline, or contact HMRC and ask them to review or withdraw the notice.

If HMRC removes the notice, filing may no longer be required. If HMRC keeps the notice active, the charity will normally need to submit the Corporation Tax return to avoid penalties.

Because charity tax rules are complex and HMRC filing requirements changed from 01/04/2026, seeking early advice can help charities avoid unnecessary stress, penalties, and compliance issues.

Need Help Responding to Your HMRC Letter?

We can help your charity understand its obligations, respond to HMRC properly, and avoid unnecessary penalties. Our team specialises in charity tax matters.

Get Free Consultation View CT600 Service

HMRC Charity Helpline

0300 123 1073

Monday to Friday, 8:30am to 5pm