The 620 is not an exact number for sure, but for there to be a sub 620, the underwriters are going to be very picky. The truth of the matter is that the vast majority of people with a sub 620 score would not get approved right now for one reason or another. If your file is really clean and the deal is a solid deal then it may go through at under 620. At sub 620, they are looking for a reason to deny you. At over 620, they are looking for reason to approve you.