A plan that meets the requirements of Internal Revenue Code Section 401(a) and the Employee Retirement Income Security Act of 1974 (ERISA) and is thus eligible for favorable tax treatment. These plans offer several tax benefits: they allow employers to deduct annual allowable contributions for each participant; contributions and earnings on those contributions are tax-deferred until withdrawn for each participant; and some of the taxes can be deferred even further through a transfer into a different type of IRA. opposite of non-qualified retirement plan.