Hi ROBERTP,
The free filing software supplied by HMRC has a set list of criteria as it is designed for use by small unrepresented companies with simple tax affairs.
Check if you can use the HMRC Corporation Tax online filing service
The above link gives the criteria that must be met for the company to use the free filing software.
If you attempt to submit a return through our free filing software, you will be asked a series of questions by the system to determine whether you are eligible to use it.
If the answers you provide prompt the service to inform you that you are unable to use our software, you will need to consult our list of commercial software suppliers.
This can be found here:
Commercial software suppliers for Corporation Tax
Thank you.