You have to verify him just as you would anyone else. Some physicians are W2 particularly if they work for a large hospital, private practice or are in academic medicine (either faculty or in training).
If they are self employed, they should still be able to show income. Either partnership, W2 out of a company they own or something.
You call the employer just as you would anyone else, you contact his accountant if necessary (ask the accountant to give a signed statement to verify the income with the doctor's permission, etc.)as options for self employed.
You are in San Antonio if I recall correctly. What is the story why this doctor isn't buying something? Texas homestead protection laws offer exceedingly nice asset protection to physicians since you can protect unlimited amount through your primary residence.
Is this doctor doing a residency, fellowship, internship or other training there at UTSA Medical Branch or be a flight surgeon in the military, I don't know, or maybe renting while their house is getting built.
I'd interview and see what the reason is for renting. Residents, interns and fellows don't make very much but often can qualify for big loans because of their percieved earning potential. But they may very well rent while they are completing their training, (and they won't be making a huge amount during that time but they often will have big loan bills coming due.)
So those are some thoughts. Residents in the program where I trained 20 years ago were making in the low 30's. Faculty made 150K or so to start. All verifiable via HR.
--184.48.xxx.xxx