so after altering my expression to the following:

=iif(Month(Fields!Month.Value)<First(Month(Fields!Month.Value), "InboundMetricsYeartoDate"),true,false)

i'm getting closer. the results show data for the months >= to Apr 2014 but are not showing the 2015 months. NOTE: both dataset contain a year column so is my "Month" expression limiting my visibilty to only the months in 2014. The format for the Month field is "January 2014","February 2014" etc.

with that said would you suggest a nested iif statement or possibly an "OR" to add multiple criteria to the visibility group properties.

here is my attempt of the "OR" but still gettign and error:

=iif(Month(Fields!Month.Value)<First(Month(Fields!Month.Value), "InboundMetricsYeartoDate") OR (Year(Fields!Year.Value)<First(Year(Fields!Year.Value)), "InboundMetricsYeartoDate"),true,false)

thanks