ACST uses a rolling-12 month period in order to determine your eligibility for leave on any given date. The 12-month period is measured backward from the date you want to use your FMLA leave. Each time you want to use FMLA leave, we will look backward to determine how much FMLA leave you used during the preceding 12 months. For example, if you use two weeks beginning November 12, 2012, and four more weeks beginning December 1, 2012, three weeks in January 2013 and another three weeks in March 2013. To be eligible for additional leave, you would have to wait until November 12, 2013, when you would be entitled to two more weeks. Likewise, on December 1, 2013, you would be entitled to four more weeks and so on.