In general terms, a widow's exemption refers to the amount that can be deducted from taxable income by a widow, thereby reducing her tax burden. In the U.S., it usually refers to the amount exempt from state inheritance taxes on a widow's share of her husband's estate. Since it is claimed as a deduction by the widow, it has the effect of reducing her inheritance taxes.

Less frequently, the term may also apply to the amount of the property tax exemption offered to widows in certain states, such as Florida. A widow would not be eligible for this exemption if she remarries. A similar exemption is also offered to widowers in some other states.