Hello,
I am also have some problem like you, when generate MRKO for vendor withhoding tax, accounting document created include withholding tax. So my accounting manager ask me to protect this transaction. I create error message for this transaction. So before accounting staff generate MRKO will gets error when generate for vendor subject to withholding tax.
I have already try to modify user exit EXIT_RMVKON00_001 but value created in internal table T_BSEG not generate withholding tax, so I cannot modify this internal table. If any others way to modify with holding tax in MRKO please share..
Thanks you very much.
Yosep