A Roth IRA (Individual Retirement Arrangement) is a retirement plan under US law that is generally not taxed, provided certain conditions are met. The tax law of the United States allows a tax reduction on a limited amount of saving for retirement. The Roth IRA's principal difference from most other tax advantaged retirement plans is that, rather than granting a tax break for money placed into the plan, the tax break is granted on the money withdrawn from the plan during retirement.