Question about buying with creative finance

[Noah Bussanich]

Hello, I am looking into buying my first rental property and i'm exploring different creative options for financing the purchase.  I understand seller carry and assumable loans very well, however I am having a hard time understanding how to buy a house creatively when the seller still has a mortgage on the property. I'm mainly looking into Subject To and Lease options. I still don't understand the structure and how everything works in this kind of creative deal. Anything helps, Thanks!