It's much more than that.  #14 covers everything HOH so you need basically a flow chart of Q&A.  Unmarried could mean never married, divorced, widowed or the client could still be married but fall under the "considered unmarried" rules for HOH.  Then you move on to "keeping up a home" and "qualifying person" which involves a myriad of other questions.  If the answers to their questions seem incorrect, incomplete or inconsistent there may be follow-up questions or document requests.  Every situation is different, and every preparer has a different level of risk tolerance for their $545 wager.  Do I need a copy of the divorce decree?  Not necessarily.  But if the 3 prior year returns show MFJ and now they're trying to file HOH, I'm probably going to ask for it.  It certainly meets the definition of inconsistent.  Maybe there's alimony.  Maybe there's one of the "every other year" dependent clauses and we need to release an exemption.  We don't know unless we ask.  One of the biggest challenges in due diligence is knowing what to ask in what situations.