30 day notice to vacate

[Zach Becker]

I recently closed on a duplex in Indianapolis that had an existing tenant on one side.  He is on a month to month lease (been there less than a year) and pays with his disability checks that come on the 3rd each month.  I would like to give him his 30 day notice to vacate the property so that rehab can begin on his side as soon as we are done on vacant side.  Is anyone familiar with process of issuing the notice, is there a specific form? Or can it be informal written form and/or verbal?

Also, when mentioning over the phone that we will likely issue his 30 day notice tomorrow on Dec. 1st, he states he will have to use his disability check on the 3rd to get into his new place (hinting that he won't be able to pay me current rent check from previous owner).  Do I even worry about chasing down the rent check and just pray he leaves in a timely fashion? 

Any and all advice would be welcomed, thank you in advance!