Outstanding federal executives could get substantial (and free) lifetime pension boosts in addition to annual bonuses worth up to $9,500 under the Carter administration plan to revamp the upper reaches of the bureaucracy.

Part of President Carter's reform of the civil service would be creation of a Senior Executive Service for 9,000-plus top career and political appointees in Grades 16, 17 and 18. Under the SES, officials would trade job tenure for the chance to get ahead quicker, have more interesting and varied assignments, and to earn bonuses of up to 20 per cent of salary each year. The pay range for that group now runs from $42,423 to $47, 500.

The bonuses, which would range from 5 percent to 20 percent, would go to an estimated half of the SES members each year. Good, but not outstanding, workers would get smaller bonuses, or straight pay. Marginal supergraders could be put back in competent, fired more easily than now.

Legislation proposed by the Carter administration would subject those bonuses to federal taxes (althouth at one point officials hoped to make them tax free.) But the biggest cash value in the plan to reward-the-best would be the effect those bonuses would have on the future retirement age now is 52 years.

Each bonus for a top-paid executive would have the effect of raising his or her future annuity by around $250 a year, for life. Although U.S. workers now pay 7 percent of income into their retirement fund, the bonuses would not be reduced by 7 percent. Executives, in other words, would have that bonus income computed toward figuring retirement benefits without having to pay 7 percent of it into the retirement fund.

During the career of an executive who did well, experts estimate that the average executives would get bonuses about half the time he or she was eligible for them. Four or five annual bonuses at the maximum 20 percent rate would, Civil Service Commission officials says, raise a life-time annual annuity between $750 and $1,000 a year. And that extra portion would not be subject to retirement contributions.

An executive who served government for 10 years and got bonuses every years (an unlikely prospect officials say) could raise his or her lifetime retirement substantially , at no extra cost. Rank-and-file employees, who would not be eligible for bonuses (or subject to the tougher standards of the SES) would not be able to increase their future pension, at no cost, unless they moved into the executive ranks.

The two features - bonuses and free and higher pensions - are the main reasons federal officials expect two out of three government executives will voluntarily move into the SES. Once the SES became officials, all new employes coming into it would have to agree to join it and abide by its tougher job rules. For many of them, it would be well worth it.

Howard G. Gamser, Washington arbitrator and formerly a top congressional staffer, is the new chairman of the Federal Services Impasses Panel. It was created in 1970 to handle top-level negotiation impasses between government agencies and unions.

Other new Carter appointees to the panel include Irving Bernstein, James E. Jones Jr., Charles J. Morris and Beverly K. Schaifer. Bernstein is a political science professor at UCLA; Jones is with the University of Wisconsin; Morris a law professor at Southern Methodist and Schaffer an economic professor at Emory University in Atlanta. They replace members named by former Presidents Nixon and Ford whose regular terms expired.