SAP TRM : how to assign default VAT Code in Business partner (TR0151)

Hi SAP guru

We are using TRM with Business Partner (BP role: TR0151 counter party) with the customer integration activated, so TRM trigger various types of Accounting document in Financial accounting and some account expects VAT exempt code.

Would any of you be able to advise me how to assign default VAT codes within Business partner for this BP role or how to enable such assignment?

Thanks in advance

Kind regards

Taro