THE D.C. COUNCIL is finally tackling the grim job of raising local taxes. A council committee has now approved a modified version of Mayor Barry's proposed tax package that would raise the sales tax from 5 to 6 percent, impose a new 6 percent tax on the price of gasoline at the pump and increase the hotel-room tax from 8 to 10 percent. Though this news isn't likely to produce any spontaneous outpouring of public gratitude, it is an important step. The tax package is part of the fiscal medicine necessary to get this city's finances in order.

The legislation now goes to the full council, where approval is expected at a scheduled meeting on Tuesday. Committee Chairman John Wilson, who could hardly be accused of rushing this proposal along, now predicts that it will pass without difficulty. If this also means new accommodation between Mr. Wilson and Mayor Barry on the matter of finances, it is encouraging; among the many items this city can no longer afford there are more than bureaucratic and program frills -- there is also this extremely costly council haggling and straggling. Mayor Barry has been trying to get the tax increases in place by July to offset a budget deficit in the current fiscal year, which ends Sept. 30. Mr. Wilson has been holding out for concessions from the mayor on the other half of the financial picture, which is spending.

Even to make a tax law effective immediately upon its passage, though, the council will have to pass the proposal on an emergency basis. Otherwise, it would have to have a "second reading" two weeks from Tuesday as well as a congressional review period of 30 legislative days -- with Congress out of town for a good part of the summer. A number of council members are understandably concerned about using emergency powers, and given the council's abuses of this procedure over the years, they have good cause to be. But this is one time when a genuine emergency can be declared and defended. Those members of Congress who have been calling for swift and decisive action should welcome a sense of emergency downtown.

Speaking of Congress, there's a job to be done on Capitol Hill, too, if members are going to live up to the responsibility they still assume for the District. The annual federal payment to the city shouldn't be a last-minute, guess-how-much arrangement. The Carter administration as well as House and Senate members who are sensitive to the District's financial plight are supporting legislation that would link the payment to the amount of local taxes collected by the city each year. Anything resembling orderly, year-to-year planning demands some formula for the federal payment. Now that the city government's leaders seem at last to be coming together in a serious effort to right old wrongs and institute sound financial policies, Congress should uphold its end of the bargain.