Hi Rashmi,
If you have decided to pay Full salary for Dec month... in the month of Jan
Check whether you have uploaded 1 month leave without Pay in IT2001 for Dec month.... If yes, then delete that entry.....
Finally go for simulation in Jan Month...
System will take retro & give you cfPtax = 200/- for Dec month.... + Ptax = 200/- for Jan month...
Regards,
Veeram