Return the last day (or first day) of the month a date falls in.
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=EOMONTH(A2, 0)EOMONTH(date, 0) returns the last day of the current month. For the first day, use EOMONTH(date, -1)+1 — the last day of the previous month plus one. The offset shifts months forward or back.
=EOMONTH(A2, -1)+1→2026-06-01First day of the month.
First day (DATE)
=DATE(YEAR(A2), MONTH(A2), 1)Builds the first day directly.
Use EOMONTH(A2, 1).
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