STARTOFMONTH

Gives the column's earliest date in the month of the filter context: on business days, the month's first business day.

Group: Time intelligence. Compatible with DAX.

Syntax

STARTOFMONTH ( <dates> )

Returns

Table. The month's first date that the column holds, as a table of one row.

Remarks

• The month is the one of the first date in the filter context. Its first date is the first one the column has in that month: on business days, 1 August 2026 is a Saturday and the month starts on Monday 3 August.
• The table of one row can be used as a value; with no date in the context, it is blank.
• Given a column, it reads the dates visible in the current filter context; in a row context, such as ADDCOLUMNS, the row becomes a filter first, so each row sees its own dates.
• Given a calendar instead of a column, it works on the calendar's own periods (fiscal years, retail months of four or five weeks, ISO weeks). A filter on a category the calendar does not define, such as a month on a calendar of weeks, can make the call an error.

Examples

First and last business day of each month

EVALUATE
SUMMARIZECOLUMNS (
    Prices[Month],
    FILTER ( VALUES ( Prices[Month] ), Prices[Month] >= DATE ( 2026, 1, 1 ) && Prices[Month] <= DATE ( 2026, 4, 1 ) ),
    "First business day", STARTOFMONTH ( Prices[Date] ),
    "Last business day", ENDOFMONTH ( Prices[Date] )
)
ORDER BY Prices[Month]

Related functions

ENDOFMONTH, STARTOFQUARTER, STARTOFYEAR, FIRSTDATE, DATESMTD.

Last updated 3 November 2026 · OpenBI Studio 0.3.74