DateSerial Function

End Of Last Month
DateSerial(Year(Date), Month(Date), 0)' ->    12/31/2006

End Of Month     
DateSerial(Year(Date), Month(Date) + 1, 0) '->    1/31/2007

First Of Last Month     
DateSerial(Year(Date), Month(Date) - 1, 0) '->    12/1/2006

First Of Next Month     
DateSerial(Year(Date), Month(Date) + 1, 1)'->     2/1/2007

First Of This Month
DateSerial(Year(Date), Month(Date), 0) '->    1/1/2007

Six Months Ago     
DateSerial(Year(Date), Month(Date) - 6, 0)'->    7/1/2006