Concerning BasicMed expiration dates, the timing pertaining to the online course (14 CFR 61.23(c)(3)(i)(C)) is written slightly differently than the regulation pertaining to the physical exam (14 CFR 61.23(c)(3)(i)(D)).
The online course with certification of completion must be completed within the past 24 calendar-months. Calendar months are also known as unit months. AC 68-1A defines this period as beginning on the first of the month and ending on the last day of the month. In the Advisory Circular’s example, a certificate of completion issued on January 15, 2020 with a 24 calendar-month duration does not expire until January 31, 2022.
However, the physical exam from a State-licensed physician and all sections of the Comprehensive Medical Examination Checklist (“CMEC”) must be completed during the previous 48 months (to the day). Here, if the physical exam is completed on January 15, 2020 with a 48 month duration, the pilot must again undergo this by January 15, 2024.