Making Pipelines Accountable to Consumers and Taxpayers Act or the MPACT Act This bill revises the authority of the Federal Energy Regulatory Commission (FERC) regarding rates and charges in connection with the transportation or sale of natural gas. Specifically, the bill provides FERC the authority to set refund effective dates by which natural gas companies must pay refunds for changes in rates or charges that are unjust, unreasonable, unduly discriminatory, or preferential.