President Carter all but conceded yesterday he will have to seek a tax cut next year to stimulate the economy but he said the question won't be fully resolved until January or February.

In his press conference yesterday, Carter said the tax cut "may come next year or perhaps later - I think next year." But he indicated it still would be "tied integrally" to his coming tax-revision package.

At the same time, the President said he is "making good progress" in working out a compromise version of the Humphrey-Hawkins jobs bill and would announce his support of the measure "within the next few days."

White House staffers met privately with congressional representatives yesterday in the latest of a series of negotiations on the issue. The two sides reportedly made further progress, but no final agreement was reached.

The bill, named for Sen. Hubert H. Humphrey (D-Minn.) and Rep. Augustus F. Hawkins (D-Cal.), would set national goals for achieving "full employment" and is being pushed vigorously by blacks and liberals. Carter endorsed the measure reluctantly during the campaign but backed away later.

The President's remarks about the tax cut were the closest he has come to endorsing a tax-reduction for 1978. Top Carter advisers have conceded recently such a move is a possiblilty, but have refused to go further.

The Administration orginally had planned to include sizable tax cuts in its tax-revision package to lure votes for the so-called "reforms" it hopes to make - most of which would requie tax increases to close existing "loopholes."

Carter hinted yesterday he may change that timing to make some of the tax-cuts take effect in 1978 rather than 1979. However, he said he still plans to include both the tax-revision and tax-cut measures in "all one package."

Speeding up the tax cut to 1978 would put the President at odds with Rep. Al Ullman (D-Ore.), chairman of the House Ways and Means Committee. Ullman said Tuesday he does not believe a tax cut is needed, and would move to block it.

Meanwhile, former President Ford told a business group in Los Angeles the President group in Los Angeles the President should seek a tax-cut now rather than waiting until 1979 because the economy will falter without more stimulus.

Ullman opposed a tax-cut in late 1976, but reversed himself later when Carter took office and proposed a two-year jobs-and-tax-cuts stimulus package. The White House is betting he will change his stand again.

Pressure for a tax-cut next year has been heightened by disclosure of a new White House forecast showing the economy is likely to be weaker than expected in late 1978 if government takes no further action.

Carter acknowledged yesterday that the tax-cut question "certainly" would be linked to the state of the economy. But he said the "major question - how much stimulus existing programs would provide - would not be answered until January.

In his remarks yesterday, Carter also told reporters his recent visit to the South Bronx had "an impact on me and my own conscience," and hinted it would influence his coming decisions on urban financing programs.

The President said he plans to tour another slum neighborhood in a visit to Detroit later this month. He said be expected the urban development bill he signed this week to provide "a framework" for "substantial improvements."