When the actual VAT amount is different than the calculated VAT amount, inside an invoice register journal in D365. and the posting profile is than updated (changed) - the value in the Actual VAT amount is reset to the calculated VAT amount.

For the scenario of the customer, the supplier calculates the VAT amount differently than D365 F&O. The right amount is added in the Actual VAT amount field but later the invoice administrator realizes that the wrong posting profile was selected. When updating the Posting profile, the Actual VAT amount is overwritten with the incorrect amount.

Since the customer is scanning invoices, the invoices are coming through an integration and the Actual VAT amount is set at the time of invoice creation. Therefore the user always has to amend the Actual VAT after the posting profile update even though originally it was correct. A possible workaround to update the posting profile before updating the actual sales tax is not applicable.

Repro steps:
1. Create an Invoice register journal.
2. Fill out all the needed fields (Supplier, Credit, Invoice number, Sales tax group, Item sales tax group.
3. Update the Actual sales tax amount to an amount that does not equal to Calculated sales tax amount.
4. Update the Posting profile on the General tab.

Expected result:
Actual sales tax amount should not be impacted by the update of the posting profile.

Real result:
Actual sales tax amount is set back to the same as Calculated sales tax amount.