July 31, 2010 (Chris Moore)

Mortgage rates are the most affordable in decades for those who can qualify for a loan.

For many, the opportunity to buy a home or refinance at this time is lost because of the tough economy and tight credit standards. But those who have secure jobs, superior credit and strong finances could do even better than the 4.54 average rate that Freddie Mac reported Thursday, according to experts.

The latest rate is the lowest for a 30-year fixed loan since Freddie began tracking rates in 1971. It also marks the fifth time in six weeks that the mortgage company has reported hitting a new average low.

Still, it’s possible to get an even lower rate if a borrower contributes more than 20 percent to the downpayment or has impeccable credit.

Credit scores do matter as one bank in Florida was offering arate of 3.375 percent on a $200,000 loan. The bank required buyers to put 20% down, have a credit score of 800 and pay $1400 in add-on fees.

Another bank which has branches in Pennsylvania, New Jersey, Maryland and West Virginia, is advertising a similar loan. But the credit score requirement is 720 and the add-on fees total $750.

Keep in mind that rates fluctuate significantly, even within a day, like airfares on a travel site. Either way, borrowers are getting good deals. The last time home loan rates were lower was during the 1950s, when most mortgages lasted just 20 or 25 years. The key is to have a sufficient down payment and a good credit score

Mortgage rates have been falling since spring. Yields on U.S. Treasury bonds have dropped as jittery investors seek safer investments. Rates tend to track the yields on Treasurys.

High unemployment, slow job growth and tight credit have made it difficult for many to purchase homes. Home sales got a boost this spring when the government offered homebuying tax credits, but activity has fizzled since those expired in April.

Sales of previously occupied homes fell 5.1 percent in June. New home sales jumped last month, but it was the second-weakest month on record and it came after sales tumbled in May.

Refinance activity has increased over the last month as homeowners seek more affordable monthly payments. But many don’t qualify for a loan because their homes don’t have sufficient value or don’t have the cash to pay for closing costs. And rates have been low for so long that many have already refinanced.