The Congressional Budget Office estimated yesterday that President Carter's January budget proposals would produce a deficit of $24.5 billion -- and possibly higher -- next fiscal year, not the $15.8 billion Carter projected.

The new figures mean it may be much harder than previously thought for Congress to balance the budget, as the White House and many lawmakers are now proposing.

The CBO also warned that the deficit for the current year, fiscal 1980, is now likely to top $47 billion rather than the $39.8 billion the administration estimated in January. Only six months ago, it stood at $29.8 billion.

Alice M. Rivlin, the agency's director, said the higher estimates for both years stem from newer inflation assumptions, soaring interest costs and added proposals for defense spending and Medicare-Medicaid outlays.

The new estimates jolted congressional leaders, who have been scurrying to find ways to cut existing spending programs in the face of rising inflation and recent turmoil in the financial markets.

Under Carter's estimates, Congress would have had to cut $20 billion in spending to balance the 1981 budget, partly to offset the reduction in tax receipts that would result from reduced federal outlays. The new figure could be close to $30 billion.

In a related development, Senate Democrats met privately yesterday to find ways of countering a GOP budget cutting proposal, but apparently reached no consensus on how to make cuts of their own.

The Democrats are hoping to head off a proposal by Sen. William V. Roth Jr. (R-Del.) that would slash fiscal 1981 spending by $42 billion to hold the overall budget within 21 percent of the gross national product. Roth has 44 cosponsors for his plan.

As all this went on, House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) took some shots yesterday at the current budget balancing fervor, telling mined to put the 1981 budget balpline in the House to make the cuts" and complaining that a balanced budget wouldn't slow inflation much anyway.

O'Neill said cutting $25 billion from the deficit would slow inflation only 0.2 percentage points. "To dismantle the programs that I've been working for as an old liberal -- I haven't changed may philosophy," he said.

O'Neill also disclosed that Carter told him at the dinner earlier this week he would veto any attempt by Congress to provide him with authority to impose wage-price controls. Although sentiment in Congress has changed some, the Lawmakers still do not appear ready to pass a controls bill.

At the same time, the administration continued work on its own budget-balancing proposals in preparation for a planned presidential speech sometime next week. Budget makers received recommendations from agencies Tuesday morning.

White House economic officials had planned to meet yesterday with House and Senate leaders as part of a round of consultations on the president's new economic plan, but the session was canceled abruptly.

Insiders say the White House still has made no decisions on which programs to cut from the proposals it sent Congress in January. However, Carter was described as still determined to put the 1981 budget into balance.

The developments came as Congress continued to chafe under its own fiscal 1980 spending limit. The lawmakers reached the ceiling on Tuesday and will not be able to take up any new spending proposals until the current limit is revised.

This has halted action on an $8 billion foreign aid package and a new Carter proposal to reinstate draft registration, among other measures.

Officials said about $15.8 billion in supplemental appropriations will be held up as well. These cover every thing from extra fuel allowances for the Pentagon to increased Veterans Administration outlays.

Rep. Robert N. Giaimo (D-Conn.), chairman of the House Budget Committee, said yesterday his panel will try to push through a revised fiscal 1980 budget resolution in time for final approval in mid-april.

However, Congress may be stymied far beyond that date if the Senate does not go along with raising the fiscal 1980 ceiling. Senate Budget Committee Chairman Edmund S. Muskie (D-Maine) is considering an alternative proposal to cut 1980 spending instead.

The $24 billion deficit estimate by the CBO is merely an updating of the president's January proposals, and assumes that Congress will go along with about $5.6 billion in suggested money-saving measures that Carter has included.

However, most lawmakers so far have dismissed those proposals as unlikely to be approved. If so, that would bring the final 1981 deficit to $31 billion. The "savings" proposals include such measures as Carter's hospital cost containment plan.

Earlier, Senate Majority Leader Robert C. Byrd (D-W.Va.) told the Senate he personally supports to a balanced budget, but cautioned that the budget-cutting effort would be painful and "those who . . . believe that we can get there by waving a wand . . . are in for a rude awakening."

Rivlin told the Senate Budget Committee at a hearing yesterday that she was opposed to wage-price controls and considered imposition of credits controls "a very difficult thing to manage." Asked when budget-cutting proposals Congress ought to consider, Rivlin replied, "All of them."