what can cause tax to be calculated on sales order line

Hi,

I want to know that what factors cause tax on the sales order line.

I dont have functional expertise in this area and we are stuck in a situation where tax is being added on the order.

We dont have receivables in the project so not sure any setups exists within order management if receivables license is not there.

Please help me understand. I have checked the order management transaction types setup as well as price lists.

The issue is pretty urgent to resolve.

Thanks

Charvie