D.C. officials are privately estimating that the city government will have a revenue shortfall of between $15 million and $20 million for the 1983 fiscal year, due to the recession's effect on property, sales and income taxes.

In addition, the city has yet to sell $6 million worth of surplus property that the budget counts on, and the City Council has not approved an $8.2 million tax increase on utilities that had been anticipated when the budget was planned.

Those factors, in addition to the new revenue shortfall estimates that sources say are now circulating among officials, mean that the city is apparently facing a total potential shortfall of more than $30 million for the fiscal year that began Oct. 1.

The most recent estimates are far bleaker than any yet to be put forward officially by Mayor Marion Barry or his budget director, Gladys Mack.

To avoid a deficit, the city would be forced to resort to spending cutbacks or other economies.

In mid-October, Barry announced that spending limits had been placed on most city agencies in anticipation of declining revenues because of nationwide economic problems.

At that time, Barry warned that city services may also have to be reduced to keep the city from running a budget deficit.

When asked yesterday about the shortfall estimates, budget director Mack said: "We are currently analyzing our revenue and spending picture for fiscal year 1983, and as yet we don't have any information to release. We are looking at revenues and trying to determine what kinds of revisions have to be made . . . . It's just too early for us to come out with specific numbers."

Yesterday Mack told members of the City Council in a hearing that in addition to any shortfall in revenue this year, the city is projecting overspending in its Medicaid program and in its unemployment compensation fund.

Mack estimated a $6 million deficit in spending for Medicaid, the health care program for the poor. She said she did not yet know the extent of the deficit problem in the unemployment fund.

Mack said the city would wait until December before making proposals on how to compensate for the revenue shortage and projected overspending. The only step it is certain to take, she said, is to borrow from the U.S. Treasury to keep the unemployment compensation fund afloat.

"We won't be certain of our '83 budget levels until December, when we have two months experience of revenue performance and we will have our budget out of Congress," she said.

Mack later provided figures indicating that the city's fiscal 1982 budget had balanced.

City agencies directly under the mayor's control are already under budget constraints to spend only at fiscal year 1982 budget levels, Mack said.

Other agencies, such as the schools and the courts, have not been placed under spending limits, she said.

Mack appeared before council members yesterday to testify in support of a budget amendment requesting a final appropriation of $24 million in this year's annual federal payment from Congress.

The additional money, which has already been authorized by the House of Representatives, would bring the payment for the current fiscal year to a record-high $361 million.

The fiscal 1983 budget was prepared by the city government on the presumption that the city would get the entire $361 million.

But the Senate has yet to approve the added federal payment money, and the council has yet to vote on authorizing the city government to spend the extra funds.

In the perhaps unlikely event that the District is denied the extra $24 million, its potential deficit would be in the plus-$50 million range.

Of the requested extra funds, $15.25 million is earmarked for Medicaid, $4.4 million to complete a package of $62.8 million in pay raises for city employees, and $4.75 million for the city retirement fund.

The added money for the retirement fund fulfills a September agreement between Barry and Frank Higgins, chairman of the D.C. Retirement Board, intended to avert having the federal government earmark a portion of the federal payment for repaying money the pension fund contends it is owed by the city.

Some members of Congress have been pressing the city to fulfill the pension fund's claim for the money.

Under the agreement the city will pay the pension fund $14.3 million plus $1.4 million in interest over the next three years.

Barry also has pledged to have the city pay, through budget supplements, any added money called for as the fund's annual debt is recalculated during the fiscal year.