CT600 filing with associated companies
With SimpleCompanyTax, file each eligible company’s CT600 and accounts with the associated-company details needed for the supported Corporation Tax calculation.
Does having associated companies mean filing one group return?
No. This service prepares an individual CT600 and accounts for each eligible company. Associated-company information is part of that company’s Corporation Tax calculation. It does not combine the accounts, profits or returns of businesses with common ownership.
Eligible companies filing their own accounts and Corporation Tax return, with associated-company information included.
Associated-company support does not include group relief claims or consolidated group accounts. Each company has its own filing.
Two companies, two sets of figures
Imagine an owner preparing filings for a trading company and a separate property company. Start a filing for each company and use its own accounts, dates and tax figures. Enter the relevant associated-company information in each filing.
The property company’s income should not be copied into the trading company’s turnover simply because they share an owner. This example explains the filing workflow, not whether the companies meet every condition in HMRC’s definition.
| Company | Its individual filing |
|---|---|
| Trading company | Its own trading figures, balance sheet and CT600. |
| Property company | Its own rental figures, balance sheet and CT600. |
Associated-company inputs and group relief are different
The supported calculation can use associated-company details. Group relief claims and consolidated accounts are outside this service. Selecting an associated-company answer does not add either capability.
If your planned return needs group relief, establish that before preparing it here. A separate company return with associated-company details is the route this page describes.
Prepare the count before starting the return
Do not decide the answer from company names alone. HMRC’s definition concerns control and includes conditions and exclusions. Read the linked guidance when establishing which companies to include.
Once your information is prepared, check the period and associated-company inputs again in the preview. A prior-year answer should not be carried forward automatically if the circumstances have changed.
What to have ready
Gather these details for your filing.
- The accounts and prepared tax figures for the individual company being filed.
- Your prepared associated-company information for the relevant period.
- Details of changes during the period that affect the information you enter.
- Separate filing records and credentials for each company.
What your filing includes
- Associated-company inputs
- Supported marginal relief calculation
- A separate CT600 for each company
- Eligible micro-entity accounts
How to file
Enter company details
Start the filing for the individual company and accounts period.
Provide associated-company figures
Enter the associated-company information and prepared financial figures.
Review and file
Check the Corporation Tax calculation and that company’s documents.
Your questions, answered
Does this include group relief?
No. Associated-company inputs are supported, but group relief claims and consolidated accounts are outside the advertised service.
Do I file one CT600 for all associated companies?
The service prepares separate filings for individual companies. It does not create a combined group return.
Should I combine associated companies’ figures before filing?
No. Prepare a separate filing using each company’s own accounts, dates and tax figures. Associated-company information is entered for the relevant individual calculation. This service does not prepare a combined group return.
Official guidance: HMRC associated companies guidance.
We file from your prepared figures. We do not provide accountancy or tax advice.