Looking to bring on investor to help secure commercial loan

[Chris Reynolds]

Hi,

I am going to purchase a 23 unit apartment building. I have the downpayment, but because I work for myself and write off quite a bit, I can not secure a bank loan. I have an investor who wants to put zero money down, but is willing to cosign the loan in order for my to qualify in the banks eyes. The property is $600,000 with $150,000 needed to make improvements from day one in order to raise the rent, and have it fully occupied (78% occupancy now) 

My question is what is a fair deal to give someone who is willing to cosign on this deal? I feel like we are buying at a good, not quite great price, but very good, and will be putting down 25% of the $750,000. Even if the building looses 20% of its value, the cosigner would not be out any money even if we had to sell, since I would be putting the original 25% equity of the building down out of my pocket. 

Any advice on a fair offer for the co-borrower, or any insight would be greatly appreciated.

Thank you,

Chris