I’m loaning my dad money and I have some contract questions

[Luis Felix]

Hello B.P.er’s, 

This is my first time loaning a large amount of money, and I would like everything to go a smooth as possible. I have an agreement with my Dad that I’ll receive 10% return on my investment upon the sale of the house. It seems very straight forward and simple. I assume I can find a template online and fill in the blanks. So my question is, is it this simple? And does anybody have any advise.