contract amendment applies retroactively for such period. 4. Employee retention credit for employers affected by California wildfires (a) In general For purposes of section 38 of the Internal Revenue Code of 1986, in the case of an eligible employer, the California wildfire employee retention credit shall be treated as a credit listed in subsection (b) of such section. For purposes of this subsection, the California wildfire employee retention credit for any taxable year is an amount equal to 40 percent of the qualified wages with respect to each eligible employee of such employer for such taxable year. For purposes of the preceding sentence, the amount of qualified wages which may be taken into account with respect to any individual shall not exceed $6,000. (b) Definitions For purposes of this section— (1) Eligible employer The term eligible employer means any employer— (A) which conducted an active trade or business on October 8, 2017, in the California wildfire disaster zone, and (B) with respect to whom the trade or business described in subparagraph (A) is inoperable on any day after October 8, 2017, and before January 1, 2018, as a result of damage sustained by reason of the wildfires to which such declaration of such area relates. (2) Eligible employee The term eligible employee means with respect to an eligible employer an employee whose principal place of employment on October 8, 2017, with such eligible employer was in the California wildfire disaster zone. (3) Qualified wages The term qualified wages means wages (as defined in section 51(c)(1) of the Internal Revenue Code of 1986, but without regard to section 3306(b)(2)(B) of such Code) paid or incurred by an eligible employer with respect to an eligible employee on any day after October 8, 2017, and before January 1, 2018, which occurs during the period— (A) beginning on the date on which the trade or business described in paragraph (1) first became inoperable at the principal place of employment of the employee immediately before the wildfires to