Estate Tax Rate Reduction Act This bill amends the Internal Revenue Code to reduce the rate for the tax on estates, gifts, and generation-skipping transfers to 20%. (Under current law, the highest rate is 40%.) The bill also exempts the budgetary effects of the tax reduction from the Pay-As-You-Go (PAYGO) rules established by the Statutory Pay-As-You-Go Act of 2010 and the FY2018 congressional budget resolution.