A tax imposed by state authorities based on the estate tax credit the U.S. federal government allows on the federal estate tax return. As this tax is imposed at the state level, the amounts owing vary state to state. And because estates are taxed at the federal level only when the minimum federal estate threshold has been surpassed, state pick-up taxes are not always applied.
States which do not have an estate, or death, tax will "pick up" additional taxes from the estate of the deceased above and beyond what is owed to the feds. This simple method of determining the estate’s state-tax liability allows states to avoid having to establish the complex guidelines for an estate tax of their own.