Here is a summary of the various taxes that may have to be paid on the death of a family member:
Federal Estate Tax. Amounts passing to a surviving spouse, and amounts passing to charity, are generally exempt from estate tax. Estate tax is generally only due on estates which, after reduction for what goes to spouse and charity, exceed the unified credit exemption equivalent, which in 2017 is $5,490,000 ($5,460,000in 2016).
Contact the IRS for a Form 706 if you need to file an estate tax return. A federal estate tax return must be filed and taxes paid within nine months of the date of death absent extension.
State Death Taxes. State laws vary. Many states impose estate taxes, which may apply in addition to federal estate taxes, or may apply even when federal estate taxes don't. Some states impose inheritance taxes, which are on individuals who receive inheritances, rather than on the estate.
Income Taxes. The federal and state income taxes of the deceased are due for the year of death. The taxes are due on the normal filing date of the following year unless an extension is requested. The spouse of the deceased may file a joint federal income tax return for the year of death. A spouse with a dependent child may file jointly for two additional years. The IRS's Publication 559, "Survivors, Executors, and Administrators" may be helpful.