Count if is in a range date of month and delete duplicates

Modified above formula, =IFERROR(IF(MATCH(E3,TEXT(C3:C40,"mmmm"),0),COUNTA(UNIQUE(FILTER($B$3:$B$40,TEXT($C$3:$C$40,"mmmm")=E3)))),0)

F3=IFERROR(ROWS(UNIQUE(FILTER($B$3:$B$40,(MONTH($C$3:$C$40)=MONTH($E3&0))*($C$3:$C$40<>"")))),"")

Copy down