For many people, the “Fiscal Cliff” deal done in January 2013, resolved potential estate tax issues: the Federal threshold for taxable estates was permanently moved to $5,000,000.00 per person (indexed for inflation, so the actual 2013 amount is $5,250,000.00). If the total estate is below that amount, there are no Federal taxes on the estate.
However, 21 states and the District of Columbia still impose some form of tax on estates. A few states impose an “inheritance tax” of varying degrees, depending on the relationship of the deceased to the person getting the inheritance. Some states are gradually eliminating the state estate tax entirely. Other states, Massachusetts for example, have a lower threshold than the Federal amount ($1,000,000.00 in Massachusetts), and cap the estate tax taxable percentage (in Massachusetts the maximum tax rate is 16%).
Forbes Magazine has an interesting and useful state-by-state map detailing estate and inheritance taxes: Where Not To Die In 2013
A more detailed analysis of the estate tax: Is the Estate Tax Doomed (NY Times)