EDATE

Date/Time Functions:
Function: EDATE() - Returns the serial number that represents the date that is the indicated number of months before or after a specified date.
2020-12-31 and -12 months is 43830 (2019-12-31)
2020-12-31 and -11 months is 43861 (2020-01-31)
2020-12-31 and -10 months is 43890 (2020-02-29)
2020-12-31 and -9 months is 43921 (2020-03-31)
2020-12-31 and -8 months is 43951 (2020-04-30)
2020-12-31 and -7 months is 43982 (2020-05-31)
2020-12-31 and -6 months is 44012 (2020-06-30)
2020-12-31 and -5 months is 44043 (2020-07-31)
2020-12-31 and -4 months is 44074 (2020-08-31)
2020-12-31 and -3 months is 44104 (2020-09-30)
2020-12-31 and -2 months is 44135 (2020-10-31)
2020-12-31 and -1 months is 44165 (2020-11-30)
2020-12-31 and 0 months is 44196 (2020-12-31)
2020-12-31 and 1 months is 44227 (2021-01-31)
2020-12-31 and 2 months is 44255 (2021-02-28)
2020-12-31 and 3 months is 44286 (2021-03-31)
2020-12-31 and 4 months is 44316 (2021-04-30)
2020-12-31 and 5 months is 44347 (2021-05-31)
2020-12-31 and 6 months is 44377 (2021-06-30)
2020-12-31 and 7 months is 44408 (2021-07-31)
2020-12-31 and 8 months is 44439 (2021-08-31)
2020-12-31 and 9 months is 44469 (2021-09-30)
2020-12-31 and 10 months is 44500 (2021-10-31)
2020-12-31 and 11 months is 44530 (2021-11-30)
2020-12-31 and 12 months is 44561 (2021-12-31)