A value-added tax is a provision in a proposal from Sen. Ben Cardin, D-Md., but Sue Walitsky, a spokeswoman for the senator, said that Cardin would want to ensure that any value-added tax did not disproportionately increase the burden on households with modest incomes. Because households with less money have to spend a greater fraction of their incomes on staples, they would pay relatively more under a tax on consumption such as a value-added tax.