Retirement Plan Regulatory Framework, ERISA, and the Internal Revenue Code
Two statutes, one plan
A qualified plan lives under two overlapping regimes. ERISA (1974) sets conduct standards: Title I (DOL) covers fiduciary duties, reporting and disclosure, and prohibited transactions; Title IV covers PBGC insurance for defined benefit plans. The Internal Revenue Code, largely through ERISA's Title II amendments, sets qualification requirements (IRC 401(a), 410, 411, 415, 416, 401(k), 401(m)) and the tax treatment of contributions and distributions (IRC 72, 402). One operational mistake can therefore create two separate problems: a fiduciary breach enforced by DOL and a qualification or excise-tax problem enforced by IRS.
Core documents and duties
ERISA 402 requires a written plan document; ERISA 102 requires a Summary Plan Description within 120 days of adoption, and a Summary of Material Modifications within 210 days after the plan year in which a material change occurs. ERISA 3(21) defines fiduciary status functionally: anyone with discretionary authority over plan management, administration, or plan assets. ERISA 406 prohibits transactions between a plan and a party in interest; IRC 4975 imposes a 15% excise tax (100% if uncorrected) on the same acts, with exemptions in ERISA 408 and DOL class exemptions.
Traps
Questions love to swap the enforcer: late participant deferral deposits are a DOL fiduciary issue, while a missed required minimum distribution is an IRS qualification issue. Do not confuse ERISA 404(c), which shields fiduciaries when participants direct investments, with 3(38) investment-manager delegation. ERISA preempts state law but does not itself grant tax deductions.
Rule of thumb: name the agency before you name the penalty.