Moderate-income Virginians now may apply for new mortgage money being offered by the Virginia Housing Development Authority (VHDA) at 13.85 percent interest to buy single-family homes.

The housing authority raised the funds through its tax-exempt mortgage revenue bond program. Last month the VHDA sold $100 million in 32-year bonds, and last Tuesday $98.3 million in proceeds from the sale were made available for lending to qualified borrowers.

The loans are made through local lenders throughout the state to qualifying first-time homebuyers.

The VHDA also raised the income limits for eligible borrowers. In Northern Virginia, the maximum adjusted income limit rose from $33,400 to $33,800 to buy a new or substantially rehabilitated home and from $31,200 to $31,600 for a resold home. For purposes of the limits, Northern Virginia consists of the cities of Alexandria, Fairfax, Fall Church, Manassas and Manassas Park and the counties of Fairfax, Arlington, Loudoun and Prince William.

The statewide income limits--except in three higher-cost areas, including Northern Virginia--now are $24,400 for a new or rehabilitated home and $18,000 for an existing home. In the Richmond area, the limits are $24,400 for new and $20,700 for existing homes, and in the Tidewater area, the limits were raised to $29,000 for new and $20,800 for existing.

The housing authority said the increases in income limits were made as a result of a higher interest rate on the new issue of bonds.

More than 22,000 families have bought homes using VHDA funds raised through the sale of tax-exempt revenue bonds, according to the housing authority, a self-supporting agency that receives no tax monies from the state.

The VHDA sold $221 million in bonds in 1979, $121 million in 1980 and $100 million in 1981. The size of the issues diminished because of federal legislation that restricted the use of mortgage revenue bonds.

The 32-year bonds used to raise the new mortgage money were sold to a syndicate of underwriters headed by Citibank, N.A.; Kidder, Peabody & Co. Inc.; Salomon Brothers Inc.; Blyth Eastman Paine Webber Inc.; E. F. Hutton & Co. Inc.; Craigie Inc.; and Wheat, First Securities Inc.

For more information, write: Homeownership Loan Programs, Virginia Housing Development Authority, 13 South 13th Street, Richmond, Virginia 23219.