A Corporation Tax (CT) return in BrightTax covers the preparation and HMRC submission of a CT600 for a company client. BrightTax supports CT returns for accounting periods ending up to 31 March 2027, using the CT 2026 form and taxonomy. This article covers how to create, open, and set up a new CT return.

• The client must exist in BrightTax as an Organisation with a company registration number and UTR recorded.
• Your HMRC filing credentials must be configured in System Settings > Account Information > HMRC Filing Details.
• Decide whether to use the Express or Advanced CT template before creating the task — see Choosing the Right CT Template for guidance.

1. From the Dashboard, click Create Task.
2. Select Corporation Tax Return from the task type list.
3. Select the accounting period or tax year.
4. Search for and select the company client.
5. Click Create Task to confirm.
6. Click Open Corporation Tax Return — the task opens in read-only mode.
7. Switch to Edit mode using the toggle in the bottom-left corner.

Before you can enter any data on the CT return, you must assign a Corporation Tax template. This is a required step and the CT return cannot be opened without it.

1. From the CT task Summary tab, click Template Details in the left-hand menu.
2. Select either Express or Advanced from the CT Template dropdown.
3. Click Save.
4. Click Open Corporation Tax Return to begin.

From the Summary tab, click Address Detail in the left-hand menu to assign or update the registered office address for the return. This should match the address held at Companies House.

BrightTax automatically applies the correct CT form based on the accounting period end date. For periods ending up to 31 March 2027, the CT 2026 form and taxonomy are used. Key changes for CT 2026 include:

• R&D PAYE cap on CT600L is now time-apportioned for short or long accounting periods
• CT600E now supports up to 12 entries for Box 195
• Enterprise Zone capital allowances are no longer applicable for periods starting on or after 1 April 2024
• CT rates and marginal relief thresholds are unchanged from 2025

The Open Corporation Tax Return button is not active

• You must assign a CT template before the Open button becomes active. Go to Template Details in the Summary tab and select a template.

I cannot find the client when creating the task

• Confirm the client is set up as an Organisation in BrightTax. CT tasks can only be created for Organisation clients.

Q: Can I change the CT template after I have started entering data?

A: No. The template cannot be changed after data has been entered. If you need to switch templates, discard and delete the task and recreate it with the correct template.

Q: Can BrightTax handle accounting periods longer than 12 months?

A: Yes. For accounting periods above 12 months, BrightTax creates separate CT tasks for each 12-month period plus any remainder. The iXBRL files are generated separately for each task.

Q: Do CT rates need to be manually updated for each year?

A: No. BrightTax applies the correct CT rates automatically based on the accounting period. You do not need to enter rates manually.