According to Fair Issac Company (My FICO) a company that provides analytic, decision making, and credit scoring services for financial service companies a credit score will go down by 40 to 110 points after being 30 days late. Further, the scoring drop will increase to 70 to 135 points after 90 days late on a mortgage payment.
The average scoring drop in a short sale, foreclosure or deed in lieu is 85 to 160 points. You need to keep in mind that in both short sales and foreclosure it is possible that the credit score drop could be closer to 200-300 points.
Credit scoring factors vary from individual to individual. The scoring change is heavily dependent on where the credit score was before the negative event took place. Both a short sale and foreclosure are considered a loan that was not paid as agreed.