Letter of Authorization

[Greg Smith]

Hello BP,

 I'm fairly new to real estate investing and I currently have a property under contract in my local area. A buyer reached out to me and stated that he has a potential buyer for my property. He stated that he needed me to sign a 'Letter of Authorization' to basically represent me as the seller when I'm just a wholesaler myself who has the property under contract with the original seller. Is this common in real estate investing or is this something I need to avoid from becoming a legal issue?