you need something like (Assumption is the parameters are for DateTime Type).

= IIF(

DateSerial(Year(Parameters!Report_From_Date.Value), Month(Parameters!Report_From_Date.Value), "1").AddMonths(1).AddDays(-1)

=

DateSerial(Year(Parameters!Report_To_Date.Value), Month(Parameters!Report_To_Date.Value), "1").AddMonths(1).AddDays(-1)

,1,0)

it will return '1' for equal, and '0' if not,

Explanation:

getting the month & year from the report parameters, calculate the Last date of the month of From Date parameter & To Date parameter, if they are equal then value will '1', else '0'.

Hope it helps.