Top federal career pay will move up to $50,100 this October if Congress goes along with the president's plan to limit the upcoming government white collar-military increase to 5.5 percent.

Federal executives, now frozen at $47,500, and members of Congress are due to get whatever amount goes to federal employes this year as part of a catch-up-with-industry raise. That raise normally would have run about 7 percent, but the president has put a 5.5 percent lid on it as part of his inflation-fighting program.

There is a chance, however, that some of the 15,000 federal "supergraders" may find pay raises shaved or blocked again because of a political pay fight between the White House and Congress, or because members of Congress don't want to risk losing the November elections by taking any kind of raise in October.

President Carter's proposal to limit the federal pay raise to 5.5 percent will not be official until he sends it to Congress later this summer in the form of an "alternate" plan. In effect Congress will have two choices before it: the 5.5 percent "alternate" plan, or the higher amount which would equal comparability with industry.

If either the Senate or House overturns the president's 5.5 percent plan by a simple majority vote, that would kill the alternate plan and put higher raises - the catch-up-with-industry amount - into effect.

But since this is an election year, and inflation and bloated bureaucracy are - again - major issues, it isn't likely federal workers will get more than 5.5 percent out of Congress.

The problem for high-level government executives could come if Congress decides to cut them out of any increase if it decides to cut itself out for political reasons. It has happened before, usually in election years.

Another cloud on the pay horizion for government executives is the president's pledge to help fight inflation by withholding 1978 increases for his appointees. That, of itself, doesn't affect career federal workers. But it could if Carter proposed freezing all executive salaries and COngress went along.

At the moment, of course, there is no plan to freeze either congressional salaries or executive pay. But both Republicans and Democrats on Capitol Hill are beginning to think about the political repercussions of an election-year increase. And when they begin doing something about it, if past practice means anything, they often take top federal executives into the freezer with them.