The Maryland estate tax is a state tax imposed on the transfer of property in a decedent's estate. Using the information from the federal return, complete the Maryland Form MET-1.At the death of a Maryland resident there are three tax systems that may apply pursuant to the estate – inheritance tax, estate tax and income tax. An estate tax return should to be filed within nine months of the decedent's death, unless the Comptroller's Office has granted an extension. An estate tax return in Maryland is a return that is due nine months from the date of death for both Maryland and the federal government. Not all estates qualify for small estate proceedings or for modified estate administration and this may be discussed with the Register of Wills' office.