The head of the federal merit system watchdog agency said yesterday it takes too much time and effort to fire or discipline incompetent government employees.

Civil Service Commission chairman Alan K. Campbell told a group of federal managers and personnel officials that a proposal in the works would remove some of the "unnecessary protections" that hinder performance and make it difficult for managers to deal with poor performers.

A CSC task force has been working on a package of legislative and administrative changes that would make it easier for managers to hire, reward, punish and fire career civil servants. Campbell spoke with President Carter about the proposals within the last few days and has been given "general approval" for some of the changes. Those new hiring and firing proposals are expected to go the the White House before Christmas.

Campbell's hard-hitting speech to a personnel management conference in Fredericksburg, Va., was his second of the day to a major federal employee group.Earlie he had talked with a professional association of federal press officers asking their support for the changes that are coming.

In recent weeks Campbell and other CSC officials have stepped up their campaign to sell Congress the public and the bureautacy on changes they plan to make in federal personnel regulations, which haven't had a major overhaul in three decades.

Campbell said the government's 2.6 million career workers can expect changes by administrative action and executive order within the coming months, and he said that Congress will be urged to act on legislative changes to make the government more managable.

The CSC chief said the federal personnel system is so rigid and "encrusted with rules and regulations" that it is almost impossible for a boss to remove an imcompetent and still do his own work. One recent CSC study showed! Campbell said, that it takes seven months to hire somebody for a job and as much as three years of red-tape and appeals to fire an employee.

He cited the case of one federal supervisor who stuck with a disciplinary action that took 18 months. At the end of that time th employee was fired, Campbell said, but the supervisor himself got an unsatisfactory performance rating because he spent so much time on the case he ignored his other duties.

Among the changes the CSC task force wants to make is to streamline the appeals system to speed up disciplinary actions, cuttint the time from, years - in some cases - to weeks.

Rigid regulations on hiring may also have to be changed. Campbell said, in order to bring more qualified women and minorities into middle and top grade federal jobs. He said that the government has almost reached a no-growth situation as far as employment is concerned. So "it is obvious, including reaching outside the federal establishment must be made" if qualified minorities are to be brought in and moved up in government.

To safeguard employee rights, Campbell said. CSC would be shorn of the dual responsibilities of making merit system rules and hearing appeals from employees under charges. He said that a separate agency should he created to hear appeals. It would be staffed by people independent of the executive branch of government serving fixed, nonrenewable terms.

Social Security offset: Several very important sentences were mixed up or dropped in yesterday's column dealing with the impact of the Senate's proposed "offset" of dependent Social Security benefits for retired federal workers.

Federal workers have their own retirement system and are not under Social Security as part of their federal employment. The sentence should have read: "The people who would be hit are federal retirees applying in the future for full dependent, or survivor's, benefits based on the Social Security earnings of a spouse." Explanation.

Who? The Senate legislation affects only persons getting a federal civilian, state or local government annunity. And it does not reduce that annunity or reduce the Social Security benefits that individual has earned for him or herself.

The only people affected by the "offset" plan approved by the Senate would be persons entitled to a public pension who applied for Social Security benefits - either as a dependent or a survivor - based on Social Security earnings of a husband or wife. In that case, if the Senate version prevails, the federal retirees' dependent or survivor benefits (based on the Social Security earnings of a spouse) would be reduced by the amount of that pension on a dollar-for-dollar basis.

When? This is a direct quote from the Senate report (P. 28): " . . . This provision would become effective payable for months starting with the month of enactment on the basis of applications filed in or after the month of enactment."