EOMONTH returns the last calendar date of a month relative to a valid starting date. It does not automatically mean the last working day or the final timestamp of that day.
Supply a valid date and offset
=EOMONTH(DATE(2026,11,3),0) returns November 30, 2026. An offset of 1 chooses the following month’s end, while -1 chooses the previous month’s end.
Use a date cell, DATE expression, or valid date serial as the first argument. Unquoted slash-separated numbers inside a formula can be evaluated as division instead of a date.
Format and interpret the result
Apply a Date format if the result appears as a serial number. A zero month offset means the month containing the start date, not zero days after it.
Month offsets are truncated when fractional. Do not use a fractional offset to represent part of a calendar month. For business-day endpoints, apply an explicitly defined working-calendar rule separately.
Test reporting boundaries
Check February in leap and nonleap years, a year-end transition, and a start date already at month-end. Verify the resulting calendar dates against a small known sample.
When filtering timestamps for a full month, use a boundary before the next month’s start rather than assuming the returned month-end date includes every later time on that day. Keep missing start dates visible and preserve the original reporting period. For deadlines, distinguish the calculated calendar endpoint from a contractual due date, which may follow additional holiday, time-zone, and cut-off rules that EOMONTH does not establish.
References
Reviewed against the linked official product guidance on November 3, 2026. Features, limits, screen labels, and access can vary by account, platform, region, and organization policy.