The Carter administration yesterday began a final round of decision-making on the president's new anti-inflation program, with expectations that Carter may unveil the plan this week, possibly in a speech to Congress tomorrow night.

The President economic advisers met privately with him late yesterday to begin narrowing options. Press secretary Jody Powell said Carter wanted more information on some proposals.

Separately, key House and Senate Democrats continued to meet in closed-door sessions to look for more ways to help balance the fiscal 1981 budget. The group agreed in principle Monday on about $11 billion in possible spending cuts, but made no additional progress yesterday.

On the basis of these and other talks, Carter is expected to propose budget cuts for fiscal 1981 and several other anti-inflation measures, possibly including restrictions on credit-card use and new means to conserve energy.

State and local officials who met with Carter yesterday said White House officials listed as a possibility a $4-a-barrel oil import fee. The extra costs would be passed on to consumers in higher gasoline prices.

Carter could impose import fees on his own, without further action in Congress.

Democrats who have been negotiating with administration representatives have been reluctant to endorse the fee idea on grounds that it would add to inflation and would be viewed by voters as a tax hike.

The administration also has been considering other new revenue-raising ideas. But congressional leaders served notice yesterday they would not try to balance the budget in part by raising revenues. This was after Senate Finance Committee Chairman Russel B. Long (D-La.) indicated privately that he opposed such moves.

The congressional group is scheduled to meet again this morning to consider the defense budget and to hear Federal Reserve Board Chairman Paul A. Volcker on the issue of credit restraints.

As it stands now the negotiators still are about $8 billion short of balancing the fiscal 1981 budget. Carter has said he would like to eliminate the deficit if possible.

Some lawmakers expressed skepticism that Congress would go along with the cuts endorsed by its leaders. The $11 billion package relies largely on proposals that Congress has rejected before, often by large majorities.

Meanwhile, in a new display of budgetary firmness, Carter vetoed a bill to increase pay and benefits for military medical personnel, charging that the bill overshot the budget and would contribute to inflation.

In a message to Congress, the president warned that "if we are to check the strong inflationary pressures that now prevail throughout the nation's economy, we must exercise genuine restraint in federal spending."

It was not immediately clear whether the House or Senate would try to override the veto. The bill, which would have affected physicians, dentists, optometrists and podiatrists, would have boosted spending by $170 million through 1985.

Carter's meeting with governors and mayors was designed mainly to prepare them for proposed cutbacks in aid to states and cities, which are expected to hit hard in the budget-balancing move.

The major cutback proposal the congressional leaders have endorsed would eliminate $2.3 billion in revenue-sharing grants to states. It is not certain whether the group will endorse a proposal to cut revenue sharing for cities and counties.

Others involve an end to Saturday mail delivery and junk-mail subsidies, and a shift to yearly, rather than twice yearly, cost-of-living adjustments in benefits for retired federal workers. This would not affect active federal employes.

Reaction from the state and local officials was cautious. New Jersey Gov. Brendan Byrne, for example said his state simply would have to live with the cuts and he reiterated his support for Carter. So did Connecticut Gov. Ella Grasso.

On Capitol Hill, however, a group of state, county and city officials headed by Minneapolis Mayor Donald Faraser warned the Senate Budget Committee that if revenue sharing is cut they will have to raise property taxes.

Carter also was rebuffed in an effort to secure the support of House Republicans for a plan to limit cost-of-living adjustments in Social Security benefits and other benefits programs to compensate for distortions in the consumer price index.

House Minority Leader John Rhodes (R-Ariz.) told administration officials late Monday night not to ask for GOP help until they could get a majority of Democrats to support the controversial idea.

In other developments:

Democratic members of a House Committee of Aging flatly opposed a proposed to tax Social Security benefits and vowed to support legislation prohibiting such a step.

A coalition of drug treatment experts childed the administration and Congress for considering cuts in aids to drug-treatment facilities in the face of an expected influx of heroin from Iran, Afghanistan and Pakistan.

Philip Anglim, who plays the title role in the play, "The Elephant Man," appealed to Congres to finance new research that might lead to the cure of disorders that afflict persons such as the one he portrays on stage.

The skepticism over whether Congress actually would go along with the budget-cutting proposals the House and Senate negotiators have discussed stems from the lawmakers' previous record in rejecting similar plans.

For example, the most widely touted of the proposals -- a plan to eliminate the states' portion of the federal revenue-sharing program -- was killed by the Senate last year, 59 to 31.

A move to require banks to collect withholding taxes on depositors' interest and dividends -- which the law-makers figured this week would bring in $3.3 billion in new revenues -- was rejected 55 to 35 by the Senate in 1976.

The House-Senate negotiators also have been talking about trimming back the school lunch program to cut subsidies for middle-income youngsters. President Ford vetoed the funds in 1975 but Congress overrode him by huge majorities.