. eligible employees may elect to contribute up to 75% ( 75 % ) of their annual base salary and 100% ( 100 % ) of their annual bonus to the serp and such employee contributions are 100% ( 100 % ) vested . in addition , the company may elect to make annual discretionary contributions on behalf of participants in the serp . each company contribution is subject to a three year vesting schedule , such that each contribution vests one third annually