Fewer homeowners lost their houses to foreclosure in the last quarter of 1985 than during the rest of the year, according to a survey by the Mortgage Bankers Association of America.

Lower interest rates, which allowed financially troubled homeowners to refinance, apparently helped reduce the rate of foreclosures.

During the same time, however, the number of households falling behind in their mortgage payments increased because of growing numbers of delinquent accounts in the South.

"The good news is that the number of homes entering foreclosure is declining," said Warren Lasko, executive vice president of the MBA. He said that the trend, which the association expects to continue, "reflects a sharp decline in interest rates allowing families to restructure their debt into more affordable obligations."

The survey found that the number of foreclosures initiated dropped from 0.24 percent of all loans in the third quarter to 0.21 percent in the fourth quarter of 1985.

The decline was across the board for all types of loans -- conventional, Federal Housing Administration-insured and Veterans Administration-guaranteed.

At the same time, however, the percentage of mortgage payments late by 30 days or more rose to 5.72 percent in the October-to-December period from 5.64 percent in the third quarter of 1985. The percentage of mortgage payments overdue by two months or more increased from 1.88 percent in the third quarter of 1985 to 1.91 percent in the final quarter of the year.

Except for the South, the results would have been different. In the Northeast and the North Central states, the percentage of overall late payments and payments late by 60 days or more declined. In the West, the percentage of overdue mortgage payments declined from 5.78 percent to 5.66 percent, but payments overdue by 60 days or more increased, from 1.90 percent to 1.95 percent.

The biggest increase, however, was in the South. There, past-due mortgage payments increased from 5.94 percent to 6.19 percent, while housing payments 60 days overdue or more increased from 1.78 percent to 2.03 percent.

Lasko blamed the increase on The foreclosure trend "reflects a sharp decline in interest rates. . . . -- Warren Lasko economic problems besetting that region. "Local economies in the South have suffered and, in some cases, have stagnated, due to problems experienced in the energy and agriculture sectors," he said.

In the District of Columbia, the total percentage of past-due mortgage payments was 9.48 percent, with 1.67 percent of all loans late by 60 days or more.

In Maryland, 6 percent of all loans were past due, with 0.88 percent of them past due by 60 days or more. In Virginia, 4.62 percent of all loans were past due, with 0.68 percent of them overdue by 60 days or more.

The percentage of loans on which foreclosures were started during the quarter was 0.30 for the District; 0.14 for Maryland, and 0.07 for Virginia.