Gift Money for Investment Property

[Sherez Mohamed]

Hello! I'm looking to invest with little of my own money down and my parents have agreed to loan me money for the down payment of a duplex. However, the banks I've been in contact with state they do not accept 'gift money'. How do I handle 'loaned' money from parents? They aren't charging interest, so I'd just need to pay them back within 2 years. 

If they were to charge me interest though, tips on how to handle that scenario as well. I'm assuming that falls under the category of private lending, but I do not have experience with that and don't know where private money falls if I'm getting a conventional loan.

Thanks in advance!