Get Quarter Starting and Ending Dates for a given Date

//whichQtr =  0 - present quarter
//           -1 - previous quarter
//            1 - next quarter
public static DateTime QuarterEnddate(DateTime curDate, int whichQtr)
{
   int tQtr = (curDate.Month - 1) / 3 + 1 + whichQtr;
   return new DateTime(curDate.Year, (tQtr * 3) + 1, 1).AddDays(-1);
}

public static DateTime QuarterStartDate(DateTime curDate, int whichQtr)
{
   return QuarterEnddate(curDate, whichQtr).AddDays(1).AddMonths(-3);
}