(a) In general. This section sets forth the rules for determining hours of service and status as a full-time employee for purposes of section 4980H. These regulations provide two methods for determining full-time employee status— the monthly measurement method, set forth in paragraph (c) of this section, and the look-back measurement method, set forth in paragraph (d) of this section. The monthly measurement method applies for purposes of determining and calculating liability under section 4980H(a) and (b), as well as, with respect to paragraph (c)(1) of this section, determination of applicable large employer status (except with respect to the weekly rule under the monthly measurement method).