If you have a need to determine a date that is a known number of months in the future or the past, then the EDATE function can be quick and easy. For instance, if you are working with expiration dates for six-month contracts, you can use the following formula:
The function takes the first date provided (in this case, using the NOW function) and uses the second parameter to determine the number of months future or past that should be calculated. The date parameter you use should resolve to a date serial number and not be a textual date.
If you use a negative value for the second parameter, then EDATE calculates a date in the past. For instance, if you wanted a date that was three months in the past, then you could use the following:
EDATE returns a date serial number; you may need to format the cell so it uses a date format that formats the returned value as you want it to appear.