The 100,000 federal and military retirees in the Washington area are due a January cost-of-living adjustment of at least 4.3 percent. The question is, will they get it?

White House and congressional budget negotiators tentatively agreed last week to freeze federal and military pensions for a year. If that freeze -- which would not apply to Social Security benefits -- becomes law it means the nearly 4 million federal and military retirees worldwide would not get another increase until January 1992. This year, retirees got a 4.7 percent increase.

COLAs are one of many items being considered by the budget summit group. Under the tentative agreement reached last week at Andrews Air Force Base, future retiree raises would be so-called diet-COLAs: 1 percentage point less than the rise in inflation. But nothing is final until they reach a compromise budget and it is passed by the House and Senate and signed by the president.

Raises for federal-military and Social Security retirees are pegged to the cost of living. Retirees are supposed to get January raises to match the percentage rise in the Consumer Price Index for the third quarter of this year over the third quarter of the previous year. Congress and the White House have frozen retiree COLAs before, and they could do it again as budget conferees look for ways to avoid automatic spending cuts (and federal furloughs) that will go into effect unless there is a budget by Oct. 1. New Union Chief

Sheila Velazco has been elected president of the National Federation of Federal Employees. She was a surprise winner at the union's Little Rock, Ark., convention and is believed to be the first woman to head a major federal union. The union says it represents 150,000 federal workers. Five of its nine national vice presidents elected at the convention are women.

Velazco faced three opponents after James M. Peirce, president for 14 years, made a surprise last-minute decision not to seek reelection. Velazco works at the Social Security Administration in Muncie, Ind. She takes over Nov. 1.

Ronald Kipke was reelected secretary-treasurer and JoAnn Ruchlewicz, of the National Park Service, was elected vice president for the Washington area. Other new vice presidents are Georgiana Kachura, Rosemary White, Thomas Ray, Arthur Guarriello, John Preston, Richard Phillips, Brenda Oistad and Sonya Constantine. No-Furlough Rally

The American Federation of Government Employees and the American Federation of State, County and Municipal Employees will picket the White House at noon protesting possible furloughs of government workers.

Next Wednesday they will take their protest to the Capitol.