I get complaint for some HODs that the overtime is not captured in last month salary including Apr 14.
I know the reason:
Departmental clerk update very late and last Friday, I still found last month 15/5 to 20/5 overtime request need to be approved.
So, I think you can change the cutoff date from 20th to 15th of the month.
By doing so, I believe no more missed update due to 10 days buffers before payment on 25th was made.