EOMONTHReturns a date representing the last day of a month which falls a specified number of months before or after another date.
EOMONTH(DATE(1969, 7, 20), 1)
start_date – The date from which to calculate the result.
months – The number of months before (negative) or after (positive) start_date to consider. The last calendar day of the calculated month is returned.
Ensure that the start_date input to the function is either a reference to a cell containing a date, a function which returns a date object such as DATE, DATEVALUE or TO_DATE, or a date serial number of the type returned by the N function. Google Sheets represents dates and times as numbers; while conversion is automatic when a human-readable date is entered into a cell, functions only accept literal dates in numeric format.
EOMONTH does not autoconvert number formats in the same way that Google Sheets does upon direct entry into cells. Therefore, EOMONTH(10/10/2000,1) is interpreted as EOMONTH(0.0005,1), the quotient of 10 divided by 10 divided by 2000.
Non-integer arguments to months will have their decimal components truncated. Therefore, EOMONTH(A2,2.6) is equivalent to EOMONTH(A2,2).
TO_DATE: Converts a provided number to a date.
N: Returns the argument provided as a number.
EDATE: Returns a date a specified number of months before or after another date.
DATEVALUE: Converts a provided date string in a known format to a date value.
DATE: Converts a year, month, and day into a date.
Returns the date of the last day of a month which falls months away from the given start_date.