This bill amends the Tax Cuts and Jobs Act of 2017 (P.L. 115-97) to provide that the net operating carryforward and carryback modifications in that Act are effective for net operating losses arising in taxable years beginning after December 31, 2017 (instead of tax years ending after December 31, 2017). The bill also allows an extension of the deadline for filing an application for a tentative carryback adjustment for net operating losses arising before January 1, 2018, and ending after December 31, 2017.