referred to in subsection (b)(2) of such section. (c) Qualified pandemic-Related employee benefit expenses For purposes of this section, the term qualified pandemic-related employee benefit expenses means any amount paid to or for the benefit of an employee in the employment of the employer if— (1) such amount is excludible from the gross income of the employee under section 139 of the Internal Revenue Code of 1986 by reason of being a qualified disaster relief payment described in subsection (b)(1) of such section with respect to a qualified disaster described in subsection (c)(2) of such section which was declared by reason of COVID-19, and (2) the employer elects (at such time and in such manner as the Secretary may provide) to treat such amount as a qualified pandemic-related employee benefit expense. (d) Applicable percentage For purposes of this section— (1) In general The term applicable percentage means— (A) 50 percent, in the case of qualified pandemic-related employee benefit expenses paid with respect to an essential employee, and (B) 30 percent, in any other case. (2) Essential employee The term essential employee means, with respect to any employer for any calendar quarter, any employee of such employer if a substantial portion of the services performed by such employee for such employer during such calendar quarter are essential work. (3) Essential work Not later than 30 days after the date of the enactment of this Act, the Director of the Cybersecurity and Infrastructure Security Agency shall issue a definition of essential work for the purposes of this section. In defining the term essential work , the Cybersecurity and Infrastructure Security Agency shall take into consideration its April 17th ‘‘Advisory Memorandum on Identification of Essential Critical Infrastructure Workers During Covid-19 Response’’ and shall solicit public input. (e) Special rules