"[Notice 2015-87] provides guidance on how to calculate the amount an employee is required to contribute toward the cost of coverage for purposes of determining whether that coverage is affordable under the employer mandate.... The notice categorizes disability benefit recipients based on their employment status. If the recipient is still regarded as employed, the employer must continue to determine the recipient's hours of service, regardless of whether the benefits are insured or self-funded (and without regard to the 501-hour cap that applies under retirement plan rules)."