Federal workers and retirees are understandably upset by the benefit cutbacks proposed for them in the shopping list President Reagan has just sent to Congress.

But feds who are contemplating quitting, retiring, leaping from the Washington Monument, or taking other drastic action are advised to wait.

A lot must happen -- the introduction of legislation, debate and votes -- before any of the changes can become law. Workers will have plenty of advance warning before any of the pay, pension or fringe-benefit changes go into effect, if any of them do.

Congress-watchers say there is very little support there for the plan to cut federal salaries 5 percent next January. Three of every five members of Congress represent districts or were raised in cities where the federal payroll exceeds $1 million a month. Most of them are aware of the economic and political impact that a federal pay cut would have.

The proposal to raise the federal retirement age to 65 isn't likely to go anywhere until Congress completes work on a new pension system for workers hired since January 1984. Insiders say that if any change is made in the retirement age, it would probably apply only to employes with less than five years of federal service.

The administration stands its best chance of victory in the area of cutting retirement costs. It wants to slow the rise of future cost-of-living adjustments for retirees by limiting those increases to the inflation rate or the amount of the federal pay raise, whichever is lower. The administration is also asking that full cost-of-living adjustments be paid only on the first $10,000 of retirement income.

Judging from their telephone calls and letters, many federal workers and retirees think that the president's word is law. But none of the changes can be made without the approval of Congress. If that comes, it will take time.

The administration has failed in previous attempts to raise the retirement age, and Congress has also rejected attempts to freeze, much less cut, federal salaries in the past. This is a time for feds to worry, but it is much to soon to panic.