Although few people realize it, the government's 10,000 top career executives are due October pay raises ranging from $6,300 to $8,700. Those increases, which will go into effect unless Congress blocks them, mean that some senior civil servants would make more than Senate Majority Leader Howard Baker or House Speaker Thomas P. O'Neill.

That increase is substantially higher than raises proposed for other white collar government workers (average salary here about $26,000), and may come as a shock to legislators who set up the new procedures last year that make the increases automatic -- unless they change them.

Under current federal pay rules, most of the government's 1 million white collar civilian employes probably will get a 4 percent increase this year. Members of Congress who now get $60,662.50, are slated to get the same percentage increase.

Top federal pay has, heretofore, been subject to caps set in congressional pay packages -- caps designed to ensure that members of Congress make more than civil servants.

Last year Congress decided to get out of the sticky business of setting its own pay. It linked future raises to the raise white collar feds get each October, meaning congressional pay automatically will rise in tandem.

In giving up the burden of legislating their own pay each year, most members of Congress apparently assumed there no longer would be a need to put a cap on federal pay. The effect has been to set the new federal pay ceiling at the same salaries as political appointees in executive Levels 4 or 5.

The new maximum pay for the Senior Executive Service, (which will besubject to the rate paid presidential appointees at Executive Level 4, would rise in October to $67,200, up from $58,500. The new ceiling for GS (general schedule) executives, would rise from $57,500 to $63,800, the same rate that the lowest rank (Executive Level 5) presidential appointees will be paid after the October raise.

Because of the complicated changes -- which one senior official described as "only slightly less complex than the U.S. Tax Code" -- few people in Congress or the government are aware of the impact of the new pay situation that paves the way for such potentially large (automatic) executive pay raises this fall.

The Reagan administration favors pay increases for top government executives. It is doubtful the White House can or will support double-digit percentage raises one month before the November elections.

It is just as unlikely that Congress -- once aware of what last year's pay changes mean -- will let U.S. executives get catchup raises Congress has denied them in the past.

A Senate aide who is aware of the potential pay bonanza said "we know the White House favors an executive pay raise, and we were sort of hoping that it would happen automatically . . . ."

Another congressional staffer said it was "blowing smoke . . . to think that something like this would happen, that somebody up here wouldn't jump on it" before the big increases became effective.

This is the situation now: If Congress does nothing, the SES pay level will rise to $67,200 in October, and the pay lid for other career workers in the GS (general schedule) grades will jump to $63,800.

Members of Congress would get the same 4 percent amount they tentatively have budgeted for other, nonexecutive feds.

What is more likely to happen is that Congress will take some action to limit pay raises for senior executives to the same 4 percent amount that members and other federal workers will get.