The Extended Medicare Safety Net (EMSN) in Australia was designed to provide financial assistance to patients with high out-of-pocket (OOP) costs for medical treatment. The EMSN works on a calendar year basis. Once a patient incurs a specified amount of OOP costs, the EMSN provides additional financial benefits for the remainder of the calendar year. Its design is similar to many types of insurance products that have large deductibles and are applied on a calendar year basis. This study examines if the annual quarter within which a patient is diagnosed with cancer has an impact on the OOP costs incurred for treatment. We use administrative linked data from the Sax Institute's 45 and Up Study. Our results indicate that the timing of cancer diagnosis has a significant impact on OOP costs. Specifically, patients diagnosed in the fourth quarter of the calendar year experience significantly higher OOP costs compared to those diagnosed in the first quarter of the year. This pattern persists after controlling for different types of cancer and different stages of cancer and robustness checks. These findings have important implications for the design of the EMSN, as well as other insurance products.