The GAO estimated that 21 percent of taxpayers would owe money under the new law, versus 18 percent under the prior law, because of changes in the way withholding is calculated.

Many employers are stepping up to offer additional financial support and programs to help employees save money.

The deal for insurance company Unum's 8,500 workers: Cash for debt in exchange for unused vacation days.

Two new government edicts can make 401(k) plans more attractive, albeit less effective.