Reference > Functions reference > Date functions > Month
Returns a number from 1 to 12, representing the month of the year in which a date occurs.
date - any calendar date
Data type returned 
Originated in 
FileMaker Pro 6.0 or earlier
Month(“3/19/2014”) returns 3. This example assumes that the operating system date format is set to MM/DD/YYYY.
Month(Payment) returns 3, where Payment contains March 19, 2014. (The Payment field must be of type date.)
“Bill Due by: ” & Date(Month(DateSold) + 1;Day(DateSold);Year(DateSold)) returns Bill Due by: followed by a value that is one month later than DateSold.
Important  To avoid errors when using dates, always use four-digit years. For more information about how FileMaker Pro handles two-digit dates, see Conversion of dates with two-digit years.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas