A House subcommittee says that the Reagan administration is playing fast and loose with plans affecting the future of many federal field offices this year and next and the jobs of 25,000 to 30,000 government employes.

As a result, Rep. Patricia Schroeder (D-Colo.), chairman of the House Post Office and Civil Service subcommittee on the civil service, has introduced legislation that would require agencies to give Congress 120 days to review proposed field office changes before they take effect.

"We know there are dozens of plans to close offices being developed and implemented," Schroeder said, "but agencies refuse to tell us what they are."

Under an executive order issued by President Richard M. Nixon, major agencies are supposed to maintain regional offices in 10 cities: Atlanta, Boston, Chicago, Dallas-Fort Worth, Denver, Kansas City, New York, Philadelphia, San Francisco and Seattle. However, many agencies have scores of additional field offices.

As part of its effort to cut the budget and streamline government, the administration is pushing agencies to study whether they need so many field offices.

Edwin L. Dale Jr., director of public affairs for the Office of Management and Budget, said all the proposed field office changes have been detailed in budget documents.

However, the subcommittee staff got hold of an internal OMB computer printout that indicated that another 60,894 federal jobs would be eliminated by 1990, either through changes in the field offices or other cuts.

According to the tracking report, the biggest cuts would be at five agencies: the Health and Human Services Department (17,433 jobs), Transportation (9,681), Interior (5,758), Agriculture (4,800) and the General Services Administration (4,322). OMB officials said 25,000 to 30,000 jobs would be eliminated at field offices but did not specify from which agencies.

Because of this, Schroeder said, "Rumors run rampant of regional and field office closings, consolidations, reductions-in-force and transfers. Facts are hard to track down, but discrepancies come easily."

The subcommittee compared the administration's budget with statements that agency officials made about their field offices in response to questions from the subcommittee.

On some points, they agreed. The Housing and Urban Development Department said it would downgrade its regional offices in Boston, Kansas City, Denver and Seattle to field offices, while the Labor Department said it would abolish its regional offices in Boston, Kansas City and Seattle.

HHS said it planned to close seven regional offices of the Public Health Service, leaving units only in New York, Seattle and Dallas. The Urban Mass Transportation Administration said it would close all of its field offices.

But Ellen Battestelli, the Schroeder subcommittee aide who handled the project, said few of the letters "showed that they were in complete agreement with what the administration sent to Congress. It was very hard to follow."

For example, the subcommittee found:

The Health and Human Services Department, in its response to the subcommittee, did not mention a proposal to close an estimated 770 of the 1,340 Social Security offices and eliminate up to 18,952 jobs by 1990, mostly through the increased use of computers. The shutdown was detailed in an internal HHS memorandum last December, Battestelli said, but is not mentioned in direct communications to the subcommittee.

An OMB official, who asked not to be identified, said of the comments to the subcommittee, "That's the type of statement that we're going to raise with the agencies when they come in for their mid-year management reviews beginning in June."

In March, the Agriculture Department told the panel it had not made any decisions, but the next month, the agency's Commodity Credit Corp. closed two field offices.

The Federal Emergency Management Agency told the panel it was "examining" a plan to eliminate four of its 10 field offices; OMB had said flatly that four field offices would be eliminated. The OMB official said: "That is perfectly logical and consistent. They are on track."

"If these consolidations can be justified," Schroeder said, "it is hard to understand why the administration is so secretive."

In a May 1 letter to Schroeder, Stockman said he assumed that "each department and agency will be conferring with appropriate congressional committees after they develop specific implementation plans" about field office changes.

"Although we do not expect any rif actions in 1985 as a result of implementing management improvements in 1986," Stockman added, "it would not be appropriate for me to commit the leadership of 22 agencies to a rif policy" by assuring Schroeder that no employes would lose their jobs.

Dale said that although the final agency plans are not on the table, OMB intends to cut agency budgets for fiscal 1985 and 1986 by the amount that agencies have agreed could be saved by changing their field structures.

"They're not going to have the money, so the reductions will have to follow," Dale said. "Everything's above board. We are still following the broad outline of cutbacks that was reflected in the fiscal 1986 budget."

Stockman told Schroeder it is necessary to "eliminate all nonessential federal expenses as we work to decrease the massive deficits facing us. Officials of the departments and agencies stand ready to work with you as they move to accomplish those objectives in order to assure that your -- and our -- concerns for the continued competent provisions of service are satisfied.