The Part B plan allows qualified members with 25 years of credited service in pension Tiers 2 and 4 to retire as early as age 55 without the usual substantial Tier 2 and Tier 4 penalties for retiring before 62.

This option is available only during a three-month window period.

For school employees, the open enrollment period began June 3. It will close Aug. 31. Mayoral agencies - whose timetable is established by mayoral executive order - and other employers may establish their own 90-day enrollment periods, which must end by March 31, 2003.

Those employers include state agencies, the Health and Hospitals Corp., the City University of New York, the New York City Housing Authority, libraries, the Off-Track Betting Corp., the Triborough Bridge and Tunnel Authority, MTA New York City Transit and the Office of the Comptroller.

At city and state agencies that fail to establish a starting date, the open enrollment period will begin automatically Jan. 1, 2003.

In addition being at least 55 years old and having 25 years of creditable service, workers must be on the payroll from Feb. 1 to the day before the open enrollment period starts. Workers who are on a leave of absence without pay for 12 weeks or longer during that period will be excluded from the plan.

None of the penalties in the Tier 2 and Tier 4 pension plans will apply to workers who take advantage of Part B. In contrast to the traditional early retirement plan, which grants participants up to 36 months of extra credited service toward their pension, the 25-55 no-penalty plan does not grant extra pension credit for years of service.

Participants must file their applications for the 25-55 no-penalty plan at least 14 days before their intended retirement date. The retirement date must be during the open period.

Part B is particularly tailored for members in the Tier 2 and Tier 4 pension plans who did not sign up for 55-25 plan offered in the 1990s. Members of Tier 1 and the 55/25 plan don't benefit from Part B of the new early retirement incentive.