Just a little tweak. You might want to use "to currentdate-1" or dateadd("m",-3, currentdate+1) so that you don't include an extra day.
Note also that dateadd only subtracts the number from the month value--it's not actually calculating number of days--and if the result doesn't exist (e.g., if you subtract 3 months from 5/31/2010, there is no 2/31/2010, and the result will show the nearest possible date, e.g., 2/28/2010. So it really depends upon what you mean by "month". If it is 30 days, then use currentdate-89 to currentdate.
-LB