Hi
what do you mean by?
" Infact, a manual with holding tax is entered by the user end instead of the With holding tax that needs to be calculated by the system and all the with holding tax calculated by the system is also adjusted by a JV (adjusting entry) in the system by the user."
as explained above you adjust manually the withholding tax to be posted while outgoing payment ? so what else you are need to adjust..
could you give more details
Regards
Mahmoud EL Nady