Today is the last working day employees have to decide whether to retire from government with an iron-clad guarantee that they can get a lump-sum pension payment, or whether to stay in hopes that Congress will not eliminate the attractive option as of Oct. 1.

If the White House- congressional budget summit group eliminates the benefit -- for a $1 billion budget savings -- workers covered by the old Civil Service Retirement System would have to be retired no later than Monday to meet the deadline, if it turns out to be a deadline. Those under the new Federal Employees Retirement System must retire to meet that same deadline.

Under the CSRS, people retiring in the first three days of the month are considered to have retired that month. Retirements after the 3rd are considered as taking place the following month.

For the sake of workers who want the lump-sum option, but don't want to retire, everybody hopes this deadline talk is needless. And it could well be.

Administration sources say that while they would like to end the lump-sum benefit, they expect the budget summit group to agree to make the lump-sum payments in three equal annual installments starting Oct. 1.

Unfortunately, for on-the-fence workers, nothing is guaranteed. The conferees won't make a lump-sum decision until late next month. "If it was my mother who was panicked into retiring because she was afraid the lump-sum is going away," a White House official said, "I would tell her not to panic and not to retire."

Furlough Exception

Workers called to military duty can be paid for military or annual leave time they've accumulated if their agencies furlough, thanks to an order from Office of Personnel Management Director Constance B. Newman.

Furloughed workers can't normally be paid for annual leave because the purpose of the furlough is to save money. But Newman says that those who have been mobilized or will be can be paid for leave due them even in a furlough.

Federal employees make up about 10 percent of the nation's Reserve and National Guard units. In this area that number is much higher. Like most people called up for military duty, the reservists will make a lot less in uniform than in their civilian jobs.

Newman's plan gives them the option to collect a few more weeks' pay -- if they have the leave time -- to ease the transition from civilian to soldier. Furlough Facts

Many federal officials hope and expect that the budget deadlock will be broken before furloughs are ordered. But agencies are still making plans to furlough hundreds of thousands of people for up to 22 days. A one-day-per-week furlough means a 20 percent pay cut.

Tomorrow at noon on WNTR radio (1050 AM), Marge Marks of the Office of Personnel Management will talk about how furloughs work, and what happens to things like retirement credit, sick leave, vacation time and health insurance coverage when they are temporarily taken off the payroll.