D.C. Council Chairman Arrington Dixon asked city election officials yesterday in invalidate all 27,415 signatures filed in support of a November referendum that would permit D.C. residents tax credits of up to $1,200 per pupil for educational expenses at public and private schools.

Dixon, who is leading a coalition of city officials and community leaders who oppose the measure, contended that petitions were improperly notarized because Jo Ann Willis, whose notary seal appears on all the petitions, is also the coordinator of the initiative drive.

Section 1-501 of the District of Columbia code provides that a notary may not certify documents "in connection with matters in which he is employed as counsel, attorney or agent or in which he may be in any way interested before any of the departments [of the D.C. government]."

Dixon argued that Willis has a direct interest in the petition drive because she is an official of the initiative support committee.

Willis said yesterday that she is aware of that restriction. But, she said, she thought it referred only to financial interests. Willis said that she became a notary public in May for the sole purpose of certifying the petition signatures.

Elections Board Chairman Albert J. Beveridge said that he would refer Dixon's complaint to the board's general counsel, William Lewis. Lewis said he would make a decision early next week.

If the board determines that the notarization was improper, it could declare all of the 27,415 petition signatures are invalid. That would effectively kill the measure for this November's election.

The board could also decide that the notarization was improper, but that the signatures should still be counted since theoretically the persons signing the petitions did not know who would be notarizing the signatures. The number of signatures of the petitions is about twice the number that would be necesaary to place the measure on the ballot.

Earlier this week, the elections board gave tentative approval to the measure, saying it was a proper subject for a voter referendum and said it would be placed on the ballot in November if there were enough valid signatures to meet requirements. About 14,442 valid signatures are required to place the measure on the ballot.