In the Reagan administration's first authoritative look at the government's top career staff, a presidential commission reported yesterday that Senior Executive Service pay has gone down since 1979, when adjusted for inflation, and that the gap between federal executive pay and private sector salaries has grown to 65 percent.

"There is . . . a simple and stark reality of the marketplace: You get what you pay for; and the federal government is not paying enough to attract, develop and retain its share of the talent needed to ensure efficient, effective fulfillment of the public trust," the President's Commission on Compensation of Career Federal Executives concluded.

The commission recommended:

Increasing SES pay from one to 15 percent annually, with an 8 percent raise for the majority of SES members at the fourth step of the SES scale.

Increasing money for bonuses.

Allowing bonuses for recruiting and keeping talented workers.

Increasing the size of presidential rank awards, the highest cash awards for senior executives.

Eliminating the ceiling on total compensation a federal worker can receive in a year.

Allowing employees to be paid in cash for all unused annual leave beyond 120 hours, each year.

Severing the link between SES pay and salaries of Congress and top presidential appointees.

Cost of the recommendations is estimated at 14 percent of current SES payroll, according to the report. Annual SES payroll is $440 million, according to the Senior Executive Association, meaning the changes would cost about $61 million.

SES members are paid $65,994 to $77,500 annually, with the majority at $73,400. The commission recommended salaries of $66,544 to $89,051, meaning a typical SES member would receive $79,255.

"I believe we have a serious problem" with SES compensation, said Janet L. Norwood, U.S. commissioner of labor statistics and a member of the presidential panel. "The specific numbers and the exact right amounts will have to be looked at by the administration and Congress."

The commission has had a rocky history. It was created by executive order last April with a reporting date in August, but no members were appointed until late summer and the deadline was extended.

Chairman Ann Dore McLaughlin left in December to become labor secretary; the commission had only two months to complete its report under a new chairman, Jonna Lynne Cullen, president of J.L. Associates, a consulting firm in Alexandria.

Panel member William R. Graham, the president's science adviser, dissented from the commmission's call for "decoupling" SES pay from that of Congress and top appointees. He said it would "seriously damage the ability of the executive branch to function effectively."

Graham said in a letter attached to the report that this is partly because severing the pay link "would relieve pressure for needed increases in executive schedule salaries."

Constance Horner, head of the Office of Personnel Management, said yesterday that the proposal would "result in career senior executives as a general rule being paid more than the executive level appointees to whom they report."

Carol Bonosaro, executive director of the Senior Executive Association, which represents SES members, said the group was pleased with parts of the report but concerned about others. For example, it proposes a pay scale under which an experienced GS-15 -- who is not in the SES and does not take the career risks SES members face under the law -- would be paid more than some SES members.

House civil service subcommittee Chairman Patricia Schroeder (D-Colo.) said, "I doubt, realistically, that the recommendations will be implemented {by Congress} this year, but at least we are starting to face the issue."