D.C. City Council Chairman Sterling Tucker said yesterday that one of his mayoral rivals, council member Marion Barry (D-At-Large), had "put the cart before the horse" in advocating tax law changes before holding public hearings on them.

Last week, Barry endorsed a list of tax law changes from among 68 proposed in December by a citizens advisory panel. Barry tried to put the burden of cooperating in their enactment on Tucker and Mayor Walter E. Washington, his two main foes in the Sept. 12 Democratic mayoral primary.

Tucker made clear yesterday that he would have none of it.

Instead of agreeing to Barry's request that staff members be assigned to draft specific legislation, Tucker officially referred the tax panel's report to the council's finance and revenue committee, which Barry heads, and suggested that Barry schedule public hearings at an early date.

After the general hearings, Tucker said, "we will be able to take the next logical step: consideration of tax program reforms."

Tucker did agree, however, that Barry's committee would need additional staff personnel to work on the tax program.

Barry said he disagreed with Tucker, saying the panel, the D.C. Tax Revision Commission, had heard enough testimony on broad question's and the time had come to deal with specific legislative proposals.

Barry said he would conform the city's income tax forms to those used by the Internal Revenue Service for federal returns, and would make numerous changes in incomes and real estate tax programs.

Barry said he had not received a reply from the mayor.