Customer Tax Problem

Hi All,

I have a case for Taxes. Taxes between countries is Zero and within the Country there is tax applied.The problem as follow :

I have a customer outside the country and he has a project running within the company. Customer Master created and his country is different so when i am creating the sales Order system check the country and found that the customer is foreign and not a local one, However, because i am selling goods within country so i need to apply tax on him. Can anyone tell me how to proceed.