filtering by this month on a sharepoint list

Use SharePoint filters to Show list items due in Current Calendar Month | Pentalogic Technology

The start of Month formula :-

=DATE(YEAR([Booking date]),MONTH([Booking date]),1)

• The End of Month formula :-

    =DATE(YEAR([Due Date]), MONTH([Due Date])+1,1)-1

    (Which is the first day of next month - 1)

Using the same technique you can also use the following formula

The current week (Sunday to Saturday inclusive)

 Start Week =[Due Date] - WEEKDAY([Due Date]) +1
 End Week   =[Due Date] +7 - WEEKDAY([Due Date])
(For other definitions of the a week see this post)

The previous month

 Start Month =DATE(YEAR([Due Date]), MONTH([Due Date])+1, 1)
 End Month   =DATE(YEAR([Due Date]), MONTH([Due Date])+2,1)-1

The next month

 Start Month =DATE(YEAR([Due Date]), MONTH([Due Date])-1, 1)
 End Month   =DATE(YEAR([Due Date]), MONTH([Due Date]),1)-1

The current year

 Start Year =DATE(YEAR([Due Date]),1,1)
 End Year   =DATE(YEAR([Due Date]),12,31)