If the federal taxing authorities grant an extension of time for filing a return the department shall allow a like extension of time for filing upon the filing by the executor of a copy of the federal extension with the department. An extension of time for filing a return does not operate to extend the time for payment of the tax. If a person fails to file a return at the time prescribed by law or files, wilfully or otherwise, a false or fraudulent return, the department shall make the return from its own knowledge and from information it can obtain through testimony or otherwise. A return so made by the department shall be prima facie good and sufficient for all legal purposes.
Alaska Legal Code