Tax Registration error

Hello,

As part of cloud tax implementation, I am trying to setup tax registration for a legal reporting unit. There is already a supplier defined with the same name but there is no tax registration number assigned. I don't want to enable the 'Allow Duplicate Registration' as the same would allow duplicate supplier/customer registration number.

Can anyone confirm if I dont do the Tax registration setup at Legal reporting unit tax profile, what would be an impact on tax calculation ?

Thanks