In 12-Month years, months contain 4 or 5 weeks. This means the year contains at least 52 weeks. Each quarter contains 13 weeks that are divided into two “4 week” months and one “5 week” month. To use this configuration, define the month that contains the 5th week.
From Which month in each quarter will contain five weeks, indicate when the 5th week occurs. 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