First date of last month in a logical comparison

[VilleMasa]

I am using this expression in filter part of calculate function:

D_Employee[RowActiveFrom] < FIRSTDATE(PREVIOUSMONTH('Calendar'[date]))

However Power BI doesn't calculate it and gives this error:

"A function 'FIRSTDATE' has been used in a True/False expression that is used as a table filter expression. This is not allowed."

I'm just trying to compare the first date with another date and don't understand what is wrong here. Is there something to be corrected or a workaround to be used?

[amitchandak · Accepted solution]

@VilleMasa , for the first date of last month

eomonth('Calendar'[date],-2)+1

In case of measure you might have to use

eomonth(max('Calendar'[date]) ,-2)+1