The Reagan administration's proposed budgets cuts could mean the elimination of 10,000 to 12,000 nonmilitary federal jobs here -- about 3 percent of 375,000 such positions in the Washington area -- according to preliminary estimates by a congressional task force.

"There is a potential for very large scale reductions in force with thousands of people involved," said William Honig, legislative director of the Federal Government Service Task Force, a newly formed caucus of representatives whose districts include substantial numbers of federal workers.

Honig stressed that the task force figures are "raw, untested analysis" based on a weekly survey of federal agencies. "I think it is important not to create a panic," Honig said. "You don't have to be a Houdini or prognosticator to see we are talking fairly serious numbers here."

He said the Reagan administration has targeted about 90,000 job slots nationwide for elimination out of a total federal work force of about 2 million persons, or about 4 percent. Honig said most of the Washington-area jobs that may be cut involve GS-9 to GS-13 level employes earning about $21,000 to $36,300 a year.

Honig's local figures do not include persons who may lose federal jobs that are funded under the Comprehensive Employment Training Act (CETA)_ and other job programs that also are being cut. The projection also does not reflect the impact of offsetting civilian jobs, which are being created and filled by the Department of Defense in the Washington area. No estimates on the number of those jobs were available yesterday.

"There are going to be enough people displaced that it is going to have an economic impact on the local economy," said Honig, who met with representatives of the Greater Washington Area Board of Trade Monday to discuss how to help those expected to lose their jobs find new ones.

Honig said the federal employes will go through a complicated "reduction-in-force" procedure before actual layoffs occur and that all employes will get at least 30 days notice that they are being let go.

Rep. Michael Barnes (D-Md.), co-chairman of the task force, yesterday told a House District Committee hearing on the city's finances that the combination of layoffs and the elimination of presently unfilled federal slots could result in as many as 40,000 to 45,000 fewer nonmilitary federal job slots in the area. The cuts, Barnes said, would affect "the Washington area more than any other area in the country."