Metro Washington's 300,000 white-collar feds would get a 5.45 percent October raise, the 100,000 retirees here would keep getting inflation adjustments every six months and military retirees-turned-bureaucrats would have their compensation limited under a shopping list okayed yesterday by the House Post Office-Civil Service Committee (PO-CS).

The plan from the Democrat-dominated committee differs from the Reagan administration's diet menu aimed at slimming U.S. pay and retirement benefits. It runs counter to a budget package cleared earlier this month by the GOP-run Senate Governmental Affairs Committee.

President Reagan has signaled his intention to limit the October pay hike to 4.8 percent. And he wants to put federal-military retirees, who now get cost-of-living (COL) raises in March and September, on a one-raise-per-year cycle.

Both the Senate and House Budget committees sent reduced spending limits to the two "jurisdictional" committees, PO-CS and Governmental Affairs. The budget groups endorsed the 4.8 percent raise and the COL cutbacks. Governmental Affairs went along with the proposed changes. But the House unit, headed by pro-union Chairman William Ford (D-Mich.), says the 5.45 percent pay proposal (left behind by Jimmy Carter) is fairer to feds. By refusing to take action on the proposal to limit retirees to one COL adjustment every 12 months, the committee would keep the March and September raises intact.

The committee recommended numerous changes to achieve the savings mandated by the Budget Committee. One change would prohibit retired military personnel in government who get full pay and pension (not all do) from full dual compensation. Their civilian federal salaries would be reduced, based on the size of their military pensions, so that total compensation would not exceed the normal pay of their civilian federal jobs. It would also stop dual payments -- of federal salary and military pay -- for U.S. workers who train annually with reserve and National Guard units.

The committee also came out against changes cleared by the Senate Finance and House Ways and Means committees to cut Social Security costs by shifting them to the Federal Employees Health Benefits (FEHB) program. The shift would make FEHB the "primary payer" of medical bills for eligible federal retirees; these bills are now paid by Social Security. The switchover would add about $1 billion to the cost of the FEHB program (reducing Social Security outlays the same amount). The effect would be to double or triple 1982 health premiums for many government workers and retirees.

The PO-CS Committee did go along with the spending-cut total proposed by the Budget Committee, but would achieve those savings in its own way. Total savings in proposed expenditures would be the same -- $5.1 billion -- but feds would get a slightly bigger pay raise, and retirees would keep their COL raises intact.

Under current law, federal workers this October could expect about a 13.5 percent raise -- designed to bring government salaries more in line with those in private industry. The last Carter budget cut back that raise to 5.5 percent, and Reagan has proposed to shave it to no more than 4.8 percent.

Committee sources say savings that would be achieved by eliminating dual compensation for all military retirees and by cutting back dual benefits for government workers on summer training with military units would produce the same savings as those proposed by the Budget Committee.

Next step is for the Post Office-Civil Service Committee proposals to be sent back to the Budget Committee, which will review them and send a complete government-spending reduction package to the House floor. It will then be up to the House (a similar process takes place in the Senate) to decide what size raise U.s. workers will get this year and whether to keep the twice-yearly COL system or go to one raise a year.