The Reagan administration, rushing to complete its final budget under a compressed time schedule, is declaring victory in its effort to reduce next year's budget deficit by $35 billion without resorting to new taxes.

Joseph Wright, head of the Office of Management and Budget, said the administration had reached its goal of cutting the projected deficit to $100 billion for the 1990 fiscal year that starts next Oct. 1.Wright said Wednesday this would be achieved through a combination of asset sales, increased user fees, cuts in domestic programs and approximately $15 billion in savings in such programs as Medicare, farm subsidies and federal pensions.

Wright said the administration was on schedule to send Congress its $1 trillion-plus spending plan by Jan. 9. It will be President Reagan's final budget before he leaves office Jan. 20.

The $100 billion deficit target for 1990 is established by the Gramm-Rudman deficit reduction law. It compares to a deficit for the just-completed 1988 fiscal year of $155.1 billion.

The last of the OMB reviews of government agencies' budget requests was completed Wednesday, Wright said, and the agencies will now have a little over a week to make any appeals of the decisions.

He said that by Dec. 2 the administration expects all presidential decisions on appeals will be completed, meaning that with Thanksgiving, federal agencies are being given just six working days to reverse the OMB actions.

Wright said there had been very little grumbling among Cabinet secretaries over this shortened time frame, which Wright said was adopted in part to keep Reagan's final budget from becoming an issue in the presidential campaign.

Wright said he was anticipating few appeals primarily because Reagan two weeks ago stressed the need for harmony in order to meet the time table.

"It is amazing what it does for agency cooperation when the president says this is what I want you to do," Wright said.

The cuts in benefit programs will not reduce any payments to the sick or elderly, Wright said. The savings will come, in part, by slowing the rate of increase in payment schedules for doctors and hospitals under the Medicare program, he said.

Wright indicated that farm subsidies would also be a principal place the administration would look for savings, an approach the administration has tried before only to run into stiff congressional resistance.

The president's final budget is designed to provide an answer to critics who have charged it was impossible to meet the Gramm-Rudman deficit targets without imposing Draconian cuts on domestic programs or boosting taxes.

"Whoever believes you must have a major tax package just hasn't gone through a detailed review of all the programs," Wright said.

The budget will adhere to Reagan's goals of increasing defense spending by 2 percent over the rate of inflation while exempting Social Security from any cuts.

Bush has not said whether he will submit his own budget to Congress or use the Reagan budget as the basis for opening negotiations. But Bush has said that whichever approach he takes, he views cutting the budget deficit as his top priority.