Year to date always encompasses the current month, so if the dat range entered is for the year to date period, you'll be covered.
If they respond to the prompt with just yesterdays date, as you probably know, you can't get year to date nor the current month.
Assuming that they're entering a date range which encompasses at least the current year to date and current month, than you can limit rows in formulas or Running Totals using the following:
//Year formula
Year({MyTable.MyDateField}) = year(currentdate)
//Month Formula
Year({MyTable.MyDateField}) = year(currentdate)
and
Year({MyTable.MyMonthField}) = Month(currentdate)
The data should already be limited as the result of the parameter, if not, you'd place something in the record selection criteria akin to:
{MyTable.MyDateField} = {?MyDateParm}
-k
kai@informeddatadecisions.com