Hurricane Harvey and Hurricane Irma Working Family Tax Relief Act This bill amends the Internal Revenue Code to allow certain individuals affected by Hurricanes Harvey or Irma to elect to use earned income from the preceding year for the purpose of determining earned income for the earned income tax credit and the child tax credit. The bill applies to an individual: (1) whose principal place of abode on specified dates was located in the Hurricane Harvey disaster area or the Hurricane Irma disaster area, (2) who was displaced from the place of abode due to the disaster, and (3) who performed substantially all employment services in the disaster area and was so employed on the specified date. The Department of the Treasury must pay to each U.S. possession with a tax system that mirrors federal tax law (mirror code tax system) amounts equal to the loss to the possession due to this bill. For U.S. possessions that do not have a mirror code tax system, Treasury must pay an amount equal to the aggregate benefits that would have been provided to residents of the possession due to this bill if a mirror code tax system had been in effect.