The Tax Policy Center has updated its Marriage Bonus and Penalty Calculator for 2018, including the new GOP-passed tax law. The tool lets users calculate the difference in income taxes a couple would owe if filing as married or separately. “Most couples will pay lower income taxes after they are married than they would as two separate taxpayers (a marriage bonus), but some will pay a marriage penalty," TPC’s Daniel Berger writes. “Typically, couples with similar incomes will be hit with a penalty while those where one spouse earns significantly more than the other will almost always get a bonus for walking down the aisle.”