Okay, it's been 24 hours and you haven't responded back. So I'm going to make a "LOT" of assumptions here and provide feedback based on those assumptions.
- They buyer moves into the house in Oct 2018 and will be paying you monthly payments each month until the closing.
- The monthly payments are clearly identified in the sales contract.
- The month payments are a part of the agreed upon sales price identified in the sales contract.
If all the above is true, then you don't report anything until the closing in 2019. It doesn't matter that some of that sales price will be paid to you in 2018. The deal isn't "closed and final" until the closing date.
With the above, if the buyer backs out of the deal, then all monies paid you already that are not refunded are considered rent, and that situation would make the property classified as a rental for the period of time they buyer was in it and paying you to be in it.
