In 12-Month years, months contain 4 or 5 weeks for the year to contain at least 52 weeks. A discrepancy arises when 12-month years divide into quarters—each quarter has 13 weeks divided into two “4 week” months and one “5 week” month. You define the month containing the 5th week.
To define the 5th week:
From Which month in each quarter will contain five weeks, indicate when the 5th week occur.
For example, if the week happens in the third month of the quarter, select The Third Month.
To add the week using the same rule that assigns weeks to years, select Assign the extra week to a month using the same rule that’s used to assign weeks to years