At the beginning of September, the recession that began in 2008 was officially declared over by the National Bureau of Economic Research. The group found the recovery process had begun in June 2009, despite the high unemployment rate.

The biggest economic downturn since the Great Depression had finally taken a positive turn after the amount of goods and services produced by the U.S. increased, according to the New York Times. However, the collapse of the housing market left lenders cautious. A new report by Zillow Mortgage Marketplace shows that despite the upswing in economic growth, more Americans are continuing to find themselves unqualified for mortgages due to their poor credit scores.

A credit score is a general indicator of whether an applicant is responsible enough to handle a line of credit, such as a mortgage. Lenders tightened their standards after the 2008 recession in an attempt to reduce the risk of having to write off more accounts. Borrowers who fall 120 days behind on payments are considered severely delinquent and may force foreclosure.

Although mortgage rates are near record lows as the real estate market attempts to rebound, home ownership may still be far out of reach for many Americans. The report released by Zillow found three in 10 home buyers are most likely unqualified for a mortgage due to their credit scores.

The company analyzed more than 25,000 loan quotes in the month of September to retrieve its data. Zillow applicants who requested quotes for 30-year fixed mortgages with credit scores no higher than 620 were denied, even after offering to make a 15- to 25-percent down payment.

“Four years ago, in the era of easy-to-get subprime loans, many borrowers with low scores did buy homes, which in turn helped contribute to a housing bubble,” said Zillow Chief Economist Dr. Stan Humphries. “Today’s tighter credit is a predictable response by banks after the foreclosure crisis, but also keeps a cap on housing demand, which is important for the greater housing market recovery.”

Zillow found Americans with credit scores of 720 or higher have been eligible for the lowest mortgage quotes and interest rates. Borrowers with these scores were able to lock in Federal Housing Administration loan rates of 4.3 percent, while applicants with scores 100 points less didn’t even qualify.

Approximately 47 percent of Americans have scores in the 700 range, according to the Zillow study. While this may seem like a large percentage, 29 percent of Americans fall into the category of borrowers with poor credit scores at 620 or below.

“We are in an era of historically low mortgage rates, reaching levels not seen in decades,” said Humphries. “Coupled with four years of home value declines, homes are more affordable than we’ve seen for years. But the irony here is that so many Americans can’t qualify for these low rates, or can’t qualify for a mortgage at all.”

Taking the time to work on a payment history may be worth it, according to Zillow. For every 20 points added onto a credit score, the average low APR drops 0.12 percent. For a $300,000 home with a down payment of 20 percent, borrowers can save up to $6,400 over the course of a 30-year mortgage.