Although Congress has not finished work on the fiscal 1986 federal budget, major cuts are all but assured in a number of domestic programs.

Farm price supports, general revenue sharing, Medicare, community and urban development grants, land and water development programs, small business loans, rural electrification, Amtrak and federal employment are almost certain to fall victim to the next round of budget cutting.

All these programs would be cut under both the budget resolution passed by the Senate May 10 and its House counterpart awaiting floor action. In most cases the Senate cut is larger, but even if the smaller House cut is finally accepted in conference, sizable reductions are guaranteed.

That is not true in many other areas, where the House and Senate resolutions are in sharp disagreement. For example, the House wants to freeze the defense authorization at its fiscal 1985 level; the Senate would let it rise to cover inflation. The House has no freeze on Social Security and other automatic cost-of-living adjustments. But the Senate freezes them except for the Supplemental Security Income program of welfare benefits for the aged, blind and disabled. For that program, it would provide an increase on top of a cost-of-living increase.

The House would not freeze or cut most health, income-support or education programs, particularly not those for the poor and near-poor. The Senate would cut many of them, including Medicaid, student loans, community services, Job Corps, the work-incentive program for welfare recipients, school impact aid and food programs.

On all these programs, where there is sharp disagreement, there is no certainty over what Congress will do.

But reductions are all but certain on these programs:

* The House resolution assumes a 2 percent reduction in federal civilian employment over the next three years, saving $1.7 billion. The Senate version assumes a 4 percent reduction, 44,000 positions.

* An omnibus farm bill rewriting the government programs to support grains and dairy products, among other things, is under consideration. The Senate budget resolution calls for $15.1 billion in savings on farm price supports and farm credit operations over the next three years through program changes. The House bill calls for reductions of $9.7 billion.

The general revenue sharing program -- general purpose grants to local governments -- for which $4.6 billion is authorized in fiscal 1986, would be funded in full by the Senate but cut 25 percent by the House. Both chambers would allow the program to expire in 1987.

* For Medicare, the giant health-care program for 30 million aged and disabled Social Security recipients, payments to hospitals and many doctors and other providers of services would be frozen at 1985 levels, without an inflation increase. The Senate would also make additional cuts and increase the Medicare monthly premium starting in 1987. Three-year savings under the House version are estimated at $13.1 billion and at $16.3 billion under the Senate version.

* The House would reduce the administration's request for security assistance to Central America, countries that host U.S. bases and other recipients by $1 billion in fiscal 1986 and the Senate, by $400 million.

* Both resolutions would cut community development block grants by 10 percent. The House would also cut Urban Development Action Grants, designed to spur private development in cities, by 10 percent. Over three years this would amount to $1.2 billion in cuts for the two programs. The Senate version would cut the urban development grants by 20 percent in 1986 and eliminate them in 1987.

* The House would cut the development programs of the Economic Development Administration, Appalachian Regional Commission and Tennessee Valley Authority by 10 percent, or $150 million over three years. The Senate would kill the EDA and Appalachian commission and end the development programs of the TVA.

* The House would cut Small Business Administration general loan programs and SBA disaster loans by $600 million each over three years. The Senate would cut even more deeply and eliminate nonphysical disaster loans and disaster loans to farms.

* The House would cut rural housing funds by $1.7 billion over three years, the Senate, by $5.2 billion.

Both chambers would increase the Superfund, but the Senate would cut $3.3 billion over three years in budget authority for various soil and water conservation programs, water projects, land management and land purchase programs. The House resolution would make $1.8 billion in cuts over three years.

* Both resolutions would cut rural electrification loan levels by amounts ranging from $550 million in 1985 to $650 million in 1988.

To save $1.7 billion a year, the Senate would stop filling the Strategic Petroleum Reserve for three years; the House would save $1.1 billion by limiting the fill to 50,000 billion barrels a day.

* The House would cut subsidies to Amtrak, the passenger rail system, by 10 percent in 1986, or $50 million. Senate cuts would be much larger, totaling 12.5 percent in 1986, 25 percent in 1987 and 40 percent in 1988, a total of $600 million over three years.

* Both resolutions assume the enactment of a user fee for passengers and commercial items passing through customs, raising about $1.5 billion over three years.