VAT/output tax is calculated during billing and is not determined until the sales order is billed. You need to link your sales document to the corresponding billing document to get the relevant tax.
You can only get sales tax in sales order in field MWSBP.
VAT that is charged by a business and paid by its customers is known as "output VAT" (that is, VAT on its output supplies). VAT that is paid by a business to other businesses on the supplies that it receives is known as "input VAT" (that is, VAT on its input supplies). A business is generally able to recover input VAT to the extent that the input VAT is attributable to (that is, used to make) its taxable outputs. Input VAT is recovered by setting it against the output VAT for which the business is required to account to the government, or, if there is an excess, by claiming a repayment from the government.
