Sentence:  If a taxpayer dies , the executor , administrator , or legal representative must file the final return for the decedent on or before the 15 th day of the 4 th month following the close of the deceased taxpayer 's normal tax <WSD>year</WSD> . 
Meaning of the word marked with <WSD> tags:  a period of time occupying a regular part of a calendar year that is used for some particular activity