Thank you both for taking the time to read my question, look into it and respond.
Mr. Knowitall,
The statute you referenced also says under (4) that notice must be in writing. Subtenant didn't give me a specific date that he was moving at any point. Rereading my original statement, it sounds a bit unclear. To hopefully clarify: he said, paraphrasing, that he would move out either when he found a job, or by the end of summer if he failed to do so. He started looking in March, so that would be a blanket notice that covered March-August. He can give a ~6 month date-span and then move out unannounced at will within that timeframe? It sounds like based on (6) in that same statute, that the day he moved out started the 28 day notice, and he is officially terminated at the end of it. Let me know if any of the preceding information changes your conclusions any, or if I'm reading wrong/missing something.
adjusterjack,
He intends to pay the utilities, it sounds like he is just holding out so I have a reason to continue communicating with him regarding a partial April refund. So you are suggesting that I am due rent until the end of April, and that's it? Would you mind elaborating on how you concluded that the end of April was still owed, and not through the day he moved out? That will help me collect utilities, since the half-month refund he thinks he is allowed will likely exceed his portion of the utilities, so he probably believes that I owe him money.
Thanks again!

