The House Post Office-Civil Service Committee yesterday rejected President Reagan's plan to limit this year's federal pay raise to 5 percent, trim future cost-of-living adjustments for retirees and require civil servants to make payroll-deduction payments to Medicare.

All Democratic and two Republican members--Frank Wolf of Virginia and James Courter of New Jersey--voted against the civil service section of the Reagan budget. It would cut spending by slashing jobs, capping pay raises and changing the way federal annuities, now linked to the rate of inflation, are computed and paid.

Opposition to the Reagan budget from the Democratic-controlled committee was to be expected. But normally, as the expert or authorizing committee on civil service matters, it would propose alternatives to the House Budget Committee. This time, however, an aide said the majority of the PO-CS committee found the budget "so bad, so arbitrary . . . that there was nothing to patch up."

President Reagan has proposed limiting the 1982 federal pay raise to 5 percent, no matter how much private industry pay goes up. White-collar U.S. salaries are supposed to be linked to counterpart wages in industry. Both the Carter and Reagan administrations have tried to persuade Congress to approve use of a different yardstick to measure the value of salaries and fringe benefits in comparing government compensation to industry.

The president also wants Congress to limit future raises for retired federal workers to either the cost-of-living, or to the percentage pay increase U.S. workers get, whichever is less. If that system were in effect now, federal-military retirees who will get an 8.7 percent raise in next month's annuity checks would be limited to 4.8 percent, the amount of last year's general federal pay raise.

The committee, headed by Rep. William Ford (D-Mich.), also rejected the proposal that federal workers be required to pay 1.3 percent of their salary on amounts up to $32,400 for Medicare coverage that would kick in at age 65. For the typical D.C.-area federal worker, that would amount to a Medicare payment of $351 deducted from the paycheck annually.

Earlier, the House Ways and Means Committee recommended that the House Budget Committee not require federal and postal workers to pay the 1.3 percent Medicare tax.

Under House rules, the so-called authorizing committees (like Post Office-Civil Service) are supposed to send their recommendations to the Budget Committee by March 15. It then takes into account their wishes and those of the administration and attempts to work up a compromise that will be acceptable to Congress and the president. But if the authorizing committees flatly reject the president's proposed budget, some or all of his programs will be in serious trouble.