You can only mark one business worksheet as the main business. It’s not possible to set more than one as the main business.
Log in to HandiTax and Select the tax return.
Go into each business worksheet and check the Main business Y/N box next to the business name.
Make sure only one worksheet has this box ticked as Yes, and that all other worksheets are set to No.
If you're seeing an error that says details are missing, but you've already filled them in on the Business Schedule, none of the worksheets have likely been marked as the main business.
Tick Yes for one worksheet to resolve the issue.
Note: You can add up to four Business worksheets per return.