MMC Benefits Handbook
Effect on Other Benefits
Making before-tax and/or after-tax contributions has no effect on your Social Security benefits because your before-tax and after-tax contributions are subject to Social Security taxes.
Making before-tax and/or after-tax contributions to the Plan will have no effect on your other Company benefits that are salary-related. Your life, disability and retirement benefits as well as your contributions to the Stock Purchase Plan will continue to be calculated on the basis of your base salary before deductions.