The banks are offering those really low interest rates on mortgages you see advertised to those buyer’s who have a really high credit score and having a lower score will cost you more monthly because of a higher interest rate. When you see advertised rates in the 3.5% range those rates will go to the borrower’s with excellent credit.
“If you don’t have good credit, you’re not going to get that crazy low rate,” said Deborah MacKenzie, the director of counseling at the Housing Development Fund, a nonprofit group in Stamford, Conn. But she and other experts said there were tactics that consumers could use to raise their scores.”
Further reading from the New York Times, Pumping Up Your Credit Score.