A comprehensive plan for reforming the country's multiple pension systems, which would among other things make private pensions mandatory and bring all workers, such as federal employes, under the Social Security system, is due to be unveiled later this month by the President's Commission on Pension Policy.

A list of its recommendations was made available by Dallas L. Salisbury, executive director of the Employee Benefit Research Institute, who sat in on the commission's final deliberations. The recommendations include:

All private employers should be required to contribute 3 percent of wages to pension plans for all employes age 25 or older with one year of experience. Benefits would be portable if the worker changes jobs. Small businesses would get a tax credit or deduction to defray the cost of establishing these plans.

Social Security coverage should be extended to all current and future federal employes. All new state, local and nonprofit workers also would be covered. Action would be taken to eliminate both benefit "gaps" and "windfalls" to current workers. "Double dipping" would disappear. Social Security payments would not be integrated with benefits from mandatory private pensions. Federal pensions would be indexed to wage increases and adjusted once a year.

The normal retirement age of 65 for Social Security benefits should be increased to 68 over a 12-year period beginning 1990. All other pension and disability systems would be encouraged to follow suit. Contributions to Social Security would be excluded from taxable income, but benefits would be taxed and the earnings test phased out.

In addition, the commission will recommend that an employe's surviving spouse be protected or that pension benefits be divided in case of divorce. It will advocate a single agency to administer pensions, creation of a central depository for portable pension benefits, changes in laws to allow pension funds to be invested in "socially useful" ways and to give public employes the same pension protection as private employes now enjoy.

The commission was established by President Carter to formulate a national retirement income policy. Its work represents the most thorough look at pension systems since World War II. The commission is headed by C. Peter McColough, chairman of the board of Xerox Corp.

When the group's preliminary report was released last May, it generally was received unfavorably by the pension industry, which resents the added costs and regulations.

McColough admitted at the time that principles were enunciated with little regard for political and economic considerations but promised economic analyses would be forthcoming before the final report. Since these have not been released, skepticism abounds. Last week, for instance, at a meeting of enrolled actuaries, delegates voted 3 to 1 against mandatory private pensions.

Salisbury termed the commission's report "comprehensive" so far as each recommendation is concerned but expressed doubt that enough thought had been given to fitting all the pieces together. Moreover, in his opinion this "statement of idealized goals" stands little chance of being implemented in the current economic climate.

Salisbury said that the costs of maintaining preretirement standards of living for full-career workers, together with expenses for achieving the other goals outlined by the commission, would outweigh the savings recommended in the report.

The proposals most likely to be acted upon with any dispatch, he added, are those concerning the financing of Social Security because of its immediate needs. The commission recommends borrowing from other trust funds, such as disability, phasing out student benefits over a five-year period and accelerating increases in Social Security taxes that are due in 1985 to take effect in 1982. It advises borrowing from general tax revenues only as a last resort.