The White House-Congress budget stalemate could be the spark to resurrect a long-dead proposal to open an early retirement window this year for 500,000 federal and postal employes.

There are dire predictions that 100,000 federal workers -- mostly in Defense agencies -- could lose their jobs if Congress and the White House fail to agree on a budget package by the third week in November. The administration objects to a Democratic proposal to raise some taxes to help cut the deficit.

If the impasse continues, automatic across-the-board cuts required by the Gramm- Rudman-Hollings deficit reduction law could kick in, forcing agencies to start issuing pink slips.

While the situation worries many federal workers, it has cheered others who see it as providing a push to congressional Democrats and most federal unions to drop opposition to an early-out plan introduced last year by Sen. William V. Roth Jr. (R-Del.)

Early-out opponents say it would trigger a mass exodus of the best and brightest from agencies, with workers left behind forced to do double and triple duty. They say it would also open the door for contractors to move in and take over functions now performed by civil servants.

Roth's bill, introduced in the House by Rep. Helen Bentley (R-Md.), would set a three-month period when federal workers who aren't eligible to retire under current rules could leave if they take smaller pensions.

Most workers cannot retire on immediate benefits until they are at least age 55 with 30 years' service; 60 with 20 years' service or 62 with five years' service. The Roth-Bentley plan would allow federal workers a 90-day period when they could leave at any age with 25 years' service; at 50 with 20 years' service; at 55 with 15 years' service or at age 57 with five years' service. Also federal workers who are within five years of meeting normal age-service requirements could leave during the early-out period. Annuities would be reduced 2 percent for each year the retiree was under age 55.

There is no guarantee that the layoff nightmare will happen or that the Roth-Bentley bill would become law even if the layoffs take place. But if the budget crunch comes it could force many congressional opponents to do an about-face for humanitarian reasons.Plastic Money

Members of groups affiliated with the Public Employees Roundtable can now get special MasterCards, issued by the National Industrial Bank of Connecticut. The Roundtable and associated groups get a fee from the bank for each member who signs up. Those eligible for the cards include members of the Association of Government Accountants, Association of Technical and Supervisory Professionals, Classification and Compensation Society, Federal Criminal Investigators Association, Federal Executive Institute Alumni Association, Federation of Government Information Processing Councils, National Council of Social Security Management Associations, Patent Office Professional Association, Professional Managers Association and the Senior Executives Association. Job Mart

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