I am getting Tax Exempt Number field error while entering a manual sales order

Hi All,

I am getting below tax specific error while placing an order. Mainly I am seeing this error when i am entering header information and trying to save order header details to further add lines to the order but before i save, it throws below error.

Please clear the Tax Exempt Number Field. It Can be specified only if the value of Tax Handling is exempt.

Interesting observation- We are getting this issue only when I am entering orders manually. I do not see this issue when i am using copy functionality. I am further checking if i see this issue for imported orders.