Function to detrmine start and end of month

[YasserKhalil]

Hello everybody
I need your help to make this function work

Function NewMonth(sdate As Date)
    If sdate >= CDate(DateSerial(Year(sdate), 12, 17)) And CDate(sdate <= DateSerial(Year(sdate), 1, 16)) Then
        NewMonth = "January"
    End If
End Function

I tested it but I got no result
I want to check a date in a cell and if this date is greater than 17 Dec. and less than 16 Jan. the result should be "January"

[romperstomper]

The date can't be greater than 17 Dec and less than 16 Jan of the same year!

[YasserKhalil]

So how it can be fixed? I tried

Year(sdate)-1

but no vain

[YasserKhalil]

I tried this function but I got incorrect results at some dates

Function NewMonth(sdate As Date)
        If IsEmpty(sdate) Or sdate = 0 Then
            NewMonth = ""
        ElseIf sdate <= DateSerial(Year(sdate) - 1, 12, 17) And sdate >= DateSerial(Year(sdate) + 1, 1, 16) Then
            NewMonth = "January"
        ElseIf sdate >= DateSerial(Year(sdate), 12, 16) And sdate <= DateSerial(Year(sdate), 11, 17) Then
            NewMonth = "February"
        ElseIf sdate >= DateSerial(Year(sdate), 2, 17) And sdate <= DateSerial(Year(sdate), 3, 16) Then
            NewMonth = "March"
        ElseIf sdate >= DateSerial(Year(sdate), 3, 17) And sdate <= DateSerial(Year(sdate), 4, 16) Then
            NewMonth = "April"
        ElseIf sdate >= DateSerial(Year(sdate), 4, 17) And sdate <= DateSerial(Year(sdate), 5, 16) Then
            NewMonth = "May"
        ElseIf sdate >= DateSerial(Year(sdate), 5, 17) And sdate <= DateSerial(Year(sdate), 6, 16) Then
            NewMonth = "June"
        ElseIf sdate >= DateSerial(Year(sdate), 6, 17) And sdate <= DateSerial(Year(sdate), 7, 16) Then
            NewMonth = "July"
        ElseIf sdate >= DateSerial(Year(sdate), 7, 17) And sdate <= DateSerial(Year(sdate), 8, 16) Then
            NewMonth = "August"
        ElseIf sdate >= DateSerial(Year(sdate), 8, 17) And sdate <= DateSerial(Year(sdate), 9, 16) Then
            NewMonth = "September"
        ElseIf sdate >= DateSerial(Year(sdate), 9, 17) And sdate <= DateSerial(Year(sdate), 10, 16) Then
            NewMonth = "October"
        ElseIf sdate >= DateSerial(Year(sdate), 10, 17) And sdate <= DateSerial(Year(sdate), 11, 16) Then
            NewMonth = "Novermber"
        ElseIf sdate >= DateSerial(Year(sdate) + 1, 11, 17) And sdate <= DateSerial(Year(sdate) - 1, 1, 16) Then
            NewMonth = "December"
        End If
End Function

[romperstomper]

Your code isn't entirely clear, but assuming any day after 17 should belong to the following month, try this:

Function NewMonth(sdate As Date)
    If IsEmpty(sdate) Or sdate = 0 Then
        NewMonth = ""
    Else
        NewMonth = Format(DateAdd("m", -(Day(sdate) > 16), sdate), "mmmm")
    End If
End Function

[YasserKhalil]

Really wonderful , fantastic, amazing
I can't imagine it would be so easy like that
You are perfect Mr. romperstomper