The deficit-reduction agreement reached yesterday by congressional and administration negotiators includes $9 billion in additional tax revenues for fiscal 1988, but does not specify which taxes are to be raised to reach the target.

Chairmen of the tax-writing committees said it will take more tough negotiations over the next few weeks to work out the tax-increase portion of the package, which accounts for nearly one-third of the proposed deficit reduction. In fiscal 1989, the agreement calls for $14 billion in new taxes.

The House passed a $12 billion tax-increase bill last month, and the Senate Finance Committee has agreed on $11.6 billion in higher taxes for 1988. With both bills bringing in more revenue than the $9 billion target, reconciling the two would pose no mathematical difficulty.

But Reagan administration participants in the budget negotiations are opposed to some of the tax increases in the bills, and there is substantial opposition in both houses to raising taxes in any amount.

Some bitterness also is likely to remain from the course of the negotiations, in which administration officials insisted no provision of the final tax bill could reduce federal revenue. House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.) agreed to drop $2 billion in special tax breaks from his committee's tax-increase bill, but only after a protracted struggle to keep them in order to preserve support for the legislation.

In a telephone interview, Rostenkowski hinted yesterday that he might bring up the tax-cutting provisions later if the Senate version includes any such breaks -- such as a favorite of Finance Committee Chairman Lloyd Bentsen (D-Tex.) and Treasury Secretary James A. Baker III, repeal of the windfall-profits tax on oil.

"If there are losers in the bill sent over by the Senate, the deal is off," Rostenkowski said. Bentsen, for his part, said he would seek to repeal the windfall-profits tax in some other measure if it could not be in the tax bill.

Asked about objections by congressional Republicans to raising taxes, President Reagan yesterday said: "Let's wait and see what they say . . . after we get a chance to visit."

Reagan, who consistently opposed raising taxes to reduce the deficit until the stock market collapse a month ago, said the final package would not include "changes dealing with the income tax or proposals we think would be deleterious to the economy."

The amount of control the administration would have over the tax-writing process was a point of contention during the last days of the deficit-reduction negotiations. In the end, Rostenkowski and Bentsen committed themselves only to general principles about the content of the tax bill.

The bill cannot raise income-tax rates, postpone rate reductions scheduled for next year, limit annual adjustments in tax brackets to compensate for inflation or impose value-added or sales taxes. Those conditions do not appear on the written material on the plan distributed by the White House yesterday, and Baker said they were "oral representations" made to the president.

About $8.2 billion in tax increases are common to the two bills, but the administration would like to keep some of those items out of the final package. For instance, repeal of an $800 million tax- accounting benefit for defense contractors is expected to be opposed by the Treasury Department.

Of the elements in both bills, those likely to remain include extension of the 3 percent tax on telephone use (which would expire without congressional action), tightening of an estate-tax loophole created by last year's tax-revision law, faster collection of estimated tax payments by corporations and new user fees for various functions of the Internal Revenue Service, Customs Service and Bureau of Alcohol, Tobacco and Firearms.

Bentsen said he will begin the tax-writing process by revising the Finance Committee's bill in conjunction with members and the administration. The package, expected to reflect the budget agreement, will be voted on by the full Senate and then must be reconciled with the House version of tax increases.