I have a very similar personal question for prior employment years of credited service in a DB plan. . I was covered by an ERISA DB pension plan from 1974 to 1981. The vesting at that time was 10 yr cliff. I had a break in service from 1981 to 1990 when I was rehired. When I was rehired in 1990, I was advised that my prior years would be recognized as credited service once my new years of service exceeded my break in service. My annual benefit estimates eventually included benefit credit for 1974 - 1981. I retired in 2009 with 19 "new" years credited. However, the plan now says they were mistaken in crediting me with the years from 1974-1981 because I wan't vested when I left in 1981 under the schedule in effect at 1981. I believe they are mistaken and the case of DiGiacomo v Teamsters Pension Trust of Phila & Vicinity seems to back me up. (2nd Circuit Court of Appeals). Any comments? thanks