The EOMONTH function (End of Month) returns the last date of a month after adding specified number of months to a date. For example, the formula =EOMONTH(“12 Dec 2019”,1) returns “31 Jan 2020” which is one month later than the specified date.
start_date – Required. The start date to use in the calculation.
months – Required. The number of months to add after the start_date.
Below example illustrates how to get the last and first day of the current month.