Eighty-six lower-income families will be able to buy homes in Prince George's County with a mortgage interest rate of 6 3/4 percent because of a recent reallocation of funds by the Department of Housing and Urban Development.

Of the 86 mortgages available in the county, 50 will be for homes at Forestville Park by Raleigh Homes. The others have not yet been announced, a Raleigh Homes spokesman said.

The units are three- and four-bedroom, two-story town houses that sell for $55,200. With the low-interest mortgage money, monthly payments will be $446, close to $400 lower than with a standard FHA mortgage program for a house of the same price, according to the builder.

Families with incomes of between $19,000 and $29,000 a year may qualify, depending on the number of dependents. The loans are being offered on a first-come, first-served basis. The program requires a down payment of $200 plus settlement fees of $2,500.

Raleigh Homes has to commit the funds by Feb. 15 or lose them, the company spokesman said. So far, the builder has written 20 contracts for the homes, contingent on certain approvals by HUD.

The federal subsidy is likely to be among the last in a program the administration plans to phase out.