tax code determination within PO

We are getting an error (Tax code TI in procedure TAXMX is invalid) when creating a PO involving scenario below.

After adding tax code TI to procedure, I still do not see tax be included within Invoice tab of PO.

Is this scenario even possible within standard SAP? Function or user exit for determining tax code?

Scenario

Vendor (Mexico)

Plant (US)

Company Code (Mexico)

Thanks

Chris Hitzke