Use the Timestampadd function along with the date column you have and you should get what you need. Here are a couple blog posts for pointers on how to use the function:
I have an issue with the AGO function.
I have used a formulae some thing like below.
Ago("XXX"."X" , "YYY"."Y"."Month" , 3)
Similarly like for month 2 and month 1.Well the point is I need a ytd bal for the prev 3 months and current month too.
When I pass the filter as APR-2012 im getting data for APR-12,MAR-12,FEB-12,JAN-12 But
When I pass the filter as MAR-2012 im only getting data for MAR-12,FEB-12,JAN-12 but could not get data for DEC-11