So this is a report correct.
Then first you need to find the month of every birthdate.
One way is to create an option field on your request form Called "Pick a month"
it's options are January,February,March, April....etc etc etc.
Now using the FORMAT function you can get the just the month.
MOnthText is a variable type text 30
OnAfterGetRecord()
MonthText := Format(EmployeeBirthdayDate,0,'<Month Text>');
If MonthText <> "Pick a month" then CurrReport.SKIP;
So as the report rifles thru each employee it will convert the date to just the month's name.
Which it will then compare it to the month you chose on the request form.
If they don't match it skips over that employees record leaving just the ones that have a birthday in that month.