The pensions of federal and postal workers hired after January 1984 and in the future would include the best features of the current government system -- retirement at 55 and lifetime inflation protection -- as well as tax-deferred investment options under an alternative civil service retirement bill introduced last week by House Democrats.

The plan, drawn up by Reps. William D. Ford (D-Mich.) and Mary Rose Oakar (D-Ohio), would be mandatory for feds hired since January 1984 who are fully covered by Social Security.

The 2.6 million workers hired before 1984 would remain in their present retirement plan but could benefit from parts of the proposed investment package.

The Ford-Oakar bill meets most of the objections federal and postal union leaders have to a pending Senate proposal to set up a pension plan for new civil servants.

The House version offered more generous civil service benefits than either Senate option.

But none of the supplementary retirement plans gives new workers the same civil service retirement benefits as the current system.

The Senate plan doesn't require employe contributions to the civil service retirement fund unless workers choose the option allowing retirement at age 55 after 30 years' service without a reduction in benefits.

The House proposal finances the improved benefits by requiring employes to contribute about 1.3 percent of salary to the retirement fund, in addition to contributing to Social Security.

The House plan offers retirees full cost-of-living protection, while the Senate reduces it for younger retirees.

Under the House plan, workers could continue to retire on full benefit at age 55 after 30 years of service; at age 60 after 20 years or at 62 with five years.

Annuities would be based on service and the highest three years' average salary.

One Senate option requires employes to work until age 62 for full benefits; both base pensions on the high-five-year salary average.

The Senate bill allows longtime civil servants to participate in one of two optional plans with tax-deferred investment features.

One option would let workers put 10 percent of their pay into a thrift plan, with the government contributing an additional 5 percent.

The second Senate option allows for a 6 percent employe contribution, with the government matching a portion of that amount.

The House plan sets up a single thrift plan. Covered employes could invest up to 10 percent of salary, with an additional 3 percent coming from the government. Persons covered by the current civil service plan could put 10 percent of their salary into the thrift plan, but would get no contribution from the government.

Federal and postal union leaders prefer the House version, although they may seek some improvement in basic benefits. Because Ford chairs the House Post Office-Civil Service Committee, his bill should get quick approval, with the full House voting on it later this month.

The Senate Governmental Affairs Committee, chaired by Sen. William V. Roth Jr. (R-Del.), has already cleared the bill sponsored by Roth and Sen. Ted Stevens (R-Alaska) and full Senate approval is expected shortly.

Differences between the Senate and House plans will be ironed out in a conference.