Diagnosis
In the tax calculation a non-brazilian customer or vendor is used. Forsuch customers/vendors the tax region is determined automaticallydepending on the country for which the customer/vendor is defined.Since the rule for the determination is not maintained correctly thesystem cannot find the tax region. Therefore the tax calculation forsuch a customer/vendor cannot be processed.

Procedure
Please maintain the assignment 'Country -> Tax region'for the country of your customer/vendor using the customizing function
Tax regions for foreign customers/vendors