The former head of a redevelopment authority in Massachusetts pleaded guilty yesterday in U.S. District Court here to illegally accepting $1,500 from Thomas M. Zuniga, a former executive director of the D.C. Housing Finance Agency.

Dennis I. Ackerman, former head of the Taunton, Mass., redevelopment agency, said he would cooperate with a federal investigation and prosecution of codefendant Zuniga, according to a spokesman for the U.S. attorney's office.

Zuniga faces criminal charges in connection with the alleged payment of money to Ackerman at a time when Zuniga was a private consultant in Washington, before he joined the D.C. agency.

Zuniga resigned from the D.C. agency in January 1985 amid allegations that he charged $2,500 in personal expenses to an agency credit card. Zuniga repaid the money after an internal agency audit.

Zuniga and Ackerman were named in a five-count indictment on April 23 charging that they violated federal racketeering laws. The indictment alleged that in 1981 and 1982 Zuniga secretly paid $5,000 to Ackerman in exchange for Ackerman's recommending him for consulting work. As head of the Taunton agency, Ackerman helped private businesses in applying for federal redevelopment grants.

The indictment said that Ackerman steered prospective developers to Zuniga's firm, and that Ackerman then asked Zuniga for money. The indictment said the violations occurred between 1980 and 1983. Zuniga joined the D.C. Housing Finance Agency later in 1983.

U.S. District Judge John Lewis Smith scheduled sentencing for July 22. Ackerman faces up to two years imprisonment and a $10,000 fine for his guilty plea to accepting an illegal gratuity.

Federal investigators have looked into allegations that Zuniga used his D.C. government credit card for personal uses such as airline tickets for his children, but no charges have been filed. The agency helps subsidize housing for low- and moderate-income residents through the sale of municipal bonds.