Private lending for down payment

[Michael Douglas Christensen]

Hey BiggerPockets! I am curious about private lending - specifically for a down payment. Has anyone ever done this and is it legal/possible? Let me explain the hypothetical ideal scenario I'm interested in and any feedback would be great.

I'm interested in getting private lending for half of the down payment on a $100,000 property that meets the 2% rule. In other words, I would pay $15,000 and a private lender would lend me the other $15,000 for a 30% down payment. From a mortgage calculator with 3.52% interest the monthly payments on a $70,000 mortgage would be $315/month. If the property met the 2% rule it would bring in $2,000/month and with the 50% rule minus the mortgage payment I'd assume a monthly cash flow of $685. Over a year period this would be $8,220. If I split this and gave half to the lender and half to myself I would net $4,110/year or a 27.4% cash on cash return. Over 6 years I could pay back the lender's $15,000 plus an annual 10% ROI for a total of $24,000.

Has anyone ever tried something like this? The numbers seem to make sense and it seems like a win-win for everyone. I'd manage the property and the lender would sit back and relax while we both could get cash flow. I'd get into a deal with little down and a great ROI and the lender would have nice passive income. Thoughts?