The result is a date which is a number of months away from the start date. Only months are considered; days are not used for calculation.EDATE(StartDate; Months)StartDate is a date.Months is the number of months before (negative) or after (positive) the start date.What date is one month prior to 2001-03-31?=EDATE("2001-03-31";-1) returns the serial number 36950. Formatted as a date, this is 2001-02-28.EDATE wiki page.