EOMONTH function

This article describes the formula syntax and usage of the EOMONTH function in Microsoft Excel.


Returns the serial number for the last day of the month that is the indicated number of months before or after start_date. Use EOMONTH to calculate maturity dates or due dates that fall on the last day of the month.


EOMONTH(start_date, months)

The EOMONTH function syntax has the following arguments:

  • Start_date    Required. A date that represents the starting date. Dates should be entered by using the DATE function, or as results of other formulas or functions. For example, use DATE(2008,5,23) for the 23rd day of May, 2008. Problems can occur if dates are entered as text.

  • Months    Required. The number of months before or after start_date. A positive value for months yields a future date; a negative value yields a past date.

    Note: If months is not an integer, it is truncated.


  • Microsoft Excel stores dates as sequential serial numbers so they can be used in calculations. By default, January 1, 1900 is serial number 1, and January 1, 2008 is serial number 39448 because it is 39,448 days after January 1, 1900.

  • If start_date is not a valid date, EOMONTH returns the #NUM! error value.

  • If start_date plus months yields an invalid date, EOMONTH returns the #NUM! error value.


Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.







Date of the last day of the month, one month after the date in A2.



Date of the last day of the month, three months before the date in A2.


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