Opponents of an educational tax credit referendum targeted for the District of Columbia's November ballot claimed yesterday that six persons who helped collect petition signatures were not bona fide District residents but out-of-town professionals brought in to boost the referendum drive.

In a hearing before the D.C. Board of Elections and Ethics, attorney William Lightfoot said that six persons moved to Washington last spring and registered to vote just in time to begin circulating petitions. lThe six listed the same address, 339 Eighth St. NE, on their voter application forms. Several witnesses, including a next-door neighbor, testified the house is now vacant.

A petition circulator must be both a resident and a registered voter in the District of Columbia.

Initiative committee chairman Bill Keyes said the circulators were hired from around the country by Jo Ann Willis, an employe of the National Taxpayers Union, the parent organization behind the local initiative drive. Keyes acknowledged that the six all lived in the house when they first moved to Washington, but that they did intend to remain here, some to work for the taxpayers union.

H. Richard Mayberry, attorney for initiative proponents, said he would respond to the residency issue later in writing.

The proposed initiative would allow taxpayers to claim credits on their District income taxes of up to $1,200 for each child they help support in public or private schools.