Default of TAX code for Account Receivable transaction

HI Team,

We have created the tax code TAX Code-INC - GST for Accounts Receivable transactions. While creating the AR transaction, the required information was provided at both the header and line levels. However, in tax classification, the tax code we defined is being applied automatically. Manually selecting the tax code calculates the tax correctly, but the business requirement is for the tax to be selected automatically.

please share your inputs to fix the issue.

thanks