Update of Open AP Invoices for Backup Withholding Vendors

Question

Scenario:
We have open invoices that have not been paid for the vendor. We are
using Classical Withholding.
The time period required to wait before we place the vendor on backup
withholding has expired, and we change his vendor master record to have
a backup withholding code (for example, F1).
We need to update the open items, so the backup withholding percentage
(28%) will be deducted at payment time on the existing invoices. Since
this withholding code F1 is for backup withholding,the withholding
amount is greater than 0%, the update program RFWT0020 will not update
the items.
Is there an SAP program will update these existing open (unpaid) items with a
withholding code > 0%?

Answer 1

Hello Michelle,
The report RFWT0010 is used to update the withholding tax information
when changes are made in the vendor/customer data. Howver this report
has some limitations:
1. If you have posted a vendor invoice relevant to withholding tax
    at time of invoice and later you change the master data so this
    withholding tax type is not longer relevant, this change will not
    take affect for the already posted invoice, althought you run report
    RFWT0010.
    Withholding tax amount at time of invoice is already posted and
    deducted. If you later modify vendor master record and add a new
    withholding tax type relevant at time of payment, you will need to
    run report RFWT0010 before payment in order to take this withholding
    tax type into consideration, since it is relevant for payments.
    However withholding tax type at invoice is already posted and report
    RFWT0010 does not reverse this posting. Also, in the case that you
    wanted to include a withholding tax at time of invoice, it will not
    take affect for the already posted invoice.
2. The report RFWT0010 only updates withholding tax information when
    the relevant withholding tax types change. If you enter the same
    withholding tax type so there is any change for the system. This
    report updates the withholding tax information when you enter a
    different withholding tax type in the vendor master.
With report RFWT0010 the scenario would be that you already had
withholding tax data in the master record however you now need to change
same. 
For further info you can refer to the report online documentation.
Hope this is of help.
regards
Ray