Mayor Marion Barry's administration proposed yesterday elimination of almost 3,000 more jobs from the payroll of the financially crippled District of Columbia government.

The new job reductions -- including 1,000 layoffs -- would begin Oct. 1 and are in addition to the 1,540 job cuts Barry had ordered to take place before Sept. 30 in an effort to avoid a projected budget deficit of $170 million.

Yesterday, as Budget Director Gladys W. Mack proposed the most serious personnel cuts of the city's current financial crisis, City Administrator Elijah B. Rogers reluctantly predicted that efforts to completely avoid the $170 million deficit probably would fail.

Rogers, talking to a reporter, said that the city government "quite likely" would not be able to pay all of its bills by the end of the current fiscal year -- especially since Congress appears likely to grant less than the $61.8 million supplementary federal payment Barry says is needed to help balance the budget.

"It's going to be exceedingly difficult to have a truly balanced budget because we can't make additional cuts [in city programs] this late in the fiscal year," Rogers said.

Rogers said the city may have to fall back on the time-honored process of rolling over some of its bills and paying them after the start of the next fiscal year -- a practice that many municipal finance experts consider unsound and deceptive.

The Barry administration's failure to achieve a balanced budget by Sept. 30 could force yesterday's severe spending and job reduction proposals to become even more harsh in order to achieve a balanced budget by the end of the next fiscal year.

After reviewing Mack's proposals, Barry will submit his own recommendation to the City Council, which must act before the revised budget is sent to the White House and then on to Congress.

Barry did not attend the press briefing yesterday. A key aide to the mayor said that while Barry may make some internal changes on where the reductions might occur, the mayor probably will accept most of the general outline of the proposal.

Yesterday's proposal came in the form of an amendment to the proposed $1.5 billion operating budget now being considered in Congress for the 1981 fiscal year.

The amendment itself is not a complete new spending package. While it would add $3.3 million to the proposed total of the pending budget, its chief effect would be to transfer about $150 million out of some city programs and into others. Mack said this is necessary to pay for higher costs of gasoline, fuel oil and other programs affected by rising costs.

The biggest personnel reductions would be in the Department of Human Services, the city's largest, where 1,475 jobs, would be eliminated. Many of those positions are now unfilled, but at least 200 would be layoffs.

The 4,865-member police department would lose 426 positions, including 200 uniformed officers through layoffs, Rogers said. This would be in addition to the 120 positions targeted for elimination from the police payroll by Sept. 30.

Although the mayor does not have power over the school system's spending other than setting the total amount of the budget, Mack recommended that 783 of the 9,655 jobs in the schools be trimmed.

She said the proposed budget would reduce the school system's budget by $8.7 million, reflecting a drop of 8,000 estimated pupils to the new total of 99,000.

Mack said she could not accurately list the total number of layoffs in various departments, but the largest number of job reductions, most of them unfilled, would be 1,475 in Human Services and another 282 in Corrections.None of the jobs eliminated in that department would be through layoffs, Mack said. Already, 225 persons in the Corrections Department are slated to lose their jobs by Sept. 30.

Mack said the 27-person staff in Barry's own office would be reduced by two positions. Many community and union spokesmen have criticized Barry's initial budget balancing plans on grounds that cuts were not made enough into the upper levels of the bureaucracy and the mayor's own personal work force.

Some firemen had been concerned that there also would be reductions in that department. Mack said yesterday that Fire Chief Norman Richardson agreed to eliminate $1.3 million in budgeted overtime in order to avoid 300 layoffs in the 1,565-member department. The Fire Department would also be unable to fill about 55 vacant position, under the proposal outlined yesterday.

There was no indication yesterday that any of the city's 51 fire companies would have to be closed.

In March, after estimates of the city's potential budget gap ballooned from $29 million to more than $170 million, Barry proposed a four-part plan to avoid the deficit and balance a city budget drained by years of over-spending.

The plan called for $24.3 million in new and increased taxes and license fees, a $61.8 million supplementary fee federal payment, $40 million in short term loans from the U.S. Treasury and the remainder in personnel and program reductions.

The job reductions package would necessitate the loss of 1,540 positions -- including 403 through layoffs.

However, nearly every one of those elements has run into problems, except for the $40 million, which Barry had planned to borrow only if the city were required to pay back money already collected through a tax on professionals that earlier this year was thrown out by the D.C. Court of Appeals.

The House Appropriations Committee has approved only $28 million for the supplementary federal payment. While that recommendation still is pending before the full House, a key Capitol Hill aide said yesterday that the Senate probably will go along with a similarly low amount.

"I don't think we're going to be much different from the House . . . We're not too sympathetic, I would say, on the [city's request for the full] supplemental."

Barry budget officials would not say yesterday how effective the program reductions have been, or how much money had been saved through layoffs and a March 1 hiring freeze imposed by the mayor. Earlier, city officials had acknowledged that about 800 people were added to the city payroll during the first month of the freeze.

Barry has yet to disclose which license and other fees would be raised to collect an additional $3 million. A $20.2 million tax package -- including increased sales and gasoline taxes and higher property tax rates for businesses -- has been revised at least once in the face of strong opposition from the City Council.

The council's finance and revenue committee has held hearings on the tax package, but Committee Chairman John A. Wilson (D-Ward 2) said he would not act on the measure until after he reviews the proposals sent yesterday to Barry.

In order to raise the full revenues projected by Barry, the tax package would have to be in effect by July 1. Carolyn L. Smith, director of the D.C. Department of Finance and Revenue, said the council would have to enact the package by the end of next week to meet the deadline. Such action is considered a remote possibility.