Three agencies, one statute, and why that shows up in your paperwork. ERISA is organized in titles, and the titles were handed to different regulators. Title I, the labor title, gives the Department of Labor and its Employee Benefits Security Administration authority over reporting, disclosure, and fiduciary conduct. Title II amended the Internal Revenue Code to create a parallel set of tax-qualification rules, enforced by the IRS and Treasury, so a plan that satisfies the labor rules can still lose its tax status by failing the Code's. Title IV created the Pension Benefit Guaranty Corporation and the termination-insurance system for defined benefit plans. This split is not academic trivia. It is why the same person can hold one office under two different statutory names, why a plan files a Form 5500 that serves the Department of Labor and the IRS at once, and why a question about a 401(k) sometimes has two answers depending on which regulator you ask.
Who is outside it. ERISA section 4(b) excludes, in its own words, any plan that "is a governmental plan," any plan that "is a church plan ... with respect to which no election has been made under section 410(d) of title 26," plans maintained solely to comply with workers' compensation, unemployment or disability insurance laws, plans maintained outside the United States primarily for nonresident aliens, and unfunded excess benefit plans. That first exclusion is the consequential one: state and local government employees, federal employees, and public school teachers are covered by their own bodies of law instead. A church-affiliated hospital or school can be outside ERISA too unless it has elected in, which is why the same job title can carry very different protections at two employers across the street from each other. And an IRA you open at a brokerage on your own is not an employer plan at all, so it is not an ERISA plan, even though Title II of ERISA is what created IRAs in the first place.
Preemption is the sleeper provision. ERISA section 514(a) supersedes "any and all State laws insofar as they may now or hereafter relate to any employee benefit plan" it covers. The practical consequences are large and mostly invisible: a dispute over plan benefits is generally litigated as a federal case rather than a state contract case, state-law damages theories generally do not survive, and a self-insured employer health plan sits largely outside state insurance regulation, including state benefit mandates. That last one turns on two clauses working against each other. Section 514(b)(2)(A) saves state laws "which regulate insurance" from preemption, but 514(b)(2)(B) then provides that a covered plan shall not "be deemed to be an insurance company or other insurer" for purposes of such a law. So a plan that buys insurance is reached by state insurance rules through the policy, and a plan that self-insures is not. Preemption is why ERISA litigation looks so unlike ordinary insurance litigation.
What ERISA does not promise. It does not guarantee that a plan is generous, that its investment menu is cheap, or that a defined contribution balance will be adequate. It sets a floor for process and disclosure. The substantive protections it does provide have a hierarchy worth understanding: vesting rules protect what you have already earned, funding rules protect a pension's ability to pay, fiduciary rules govern how plan assets are handled, and the PBGC backstops the promise if a pension plan fails. None of those is a promise about the size of the benefit.
