TDA Rule

Tax-deferred annuity (TDA) plans are a type of 403(b) plan to which employees can voluntarily elect to make pretax or Roth contributions. TDA plans are not subject to the minimum coverage and other nondiscrimination tests that apply to most retirement plans. If an employer makes a TDA plan available to some of its employees, however, the employer must generally make it available to all nonexcludable employees. For this purpose, certain part-time, union, and student employees may be excluded.

See Keeping Your Plan In Shape, TIAA-CREF's nondiscrimination guide available in the Bookstore, for more details on excludable/non-excludable rules that apply to various types of retirement plans.