I just spoke with a customer who is trying to use Dynamics GP Web Services to import SOP Sales Orders.
He needs to import header level taxes for the sales orders, but was unable to do so--he would get an error about the amount being incorrect. He had read a forum post indicating that Web Services did not support sales taxes, so he didn't know if he was doing something wrong with his import, or if it was a limitation of Web Services.
I recommended that he contact support, as that would be the quickest way to either determine that sales taxes were not supported, or find the issue with his import.
He contacted MS support and confirmed that Dynamics GP Web Services does not support the import of sales taxes for Sales Orders. Apparently this is true for GP 10, 2010 and 2013. He was told that Web Services does support the import of sales taxes for SOP Invoices, but not for SOP Sales Orders.
I'm assuming there is some reason for this, but it seems baffling. eConnect supports the import of sales taxes for orders, so I don't understand why web services wouldn't have similar support for taxes on orders. And why Invoices are supported but Orders are not is similarly puzzling.