Jim Carrey as Scrooge in "A Christmas Carol." The tax bills currently making their way through Congress could end up making Americans less charitable. The bills that recently cleared the House and the Senate, which need to be reconciled, would have different consequences for charitable giving. But both would raise the price of donating for millions of Americans, thereby reducing how much the nation gives to charity overall. The precise impact of this tax code overhaul, however, would depend on which provisions wind up on the books. As an economist and a scholar of philanthropy who researches how public policies shape charitable giving, I have been following the pending tax proposals closely and examining their potential impact.