MERP vs HRA vs FSA vs Section 125: What Is the Difference?

MERP, HRA, health FSA and Section 125 are not four competing products. MERP is the category; HRA and health FSA are two kinds of MERP; Section 125 is the funding mechanism that lets an employee pay for one pre-tax. The genuine outlier is the HSA, which is not a MERP at all but an individually owned account under IRC §223.

Almost every comparison of these terms lines them up as rivals and asks which to pick. That framing is wrong, and it is why the answers never quite fit. Here is how they actually relate, and which combinations can be held at once.

MERP Is the Category, Not a Product

A Medical Expense Reimbursement Plan is any written, employer-sponsored arrangement that reimburses employees for qualified medical expenses under IRC §105(b). It is a family name.

HRAs are MERPs. ICHRAs and QSEHRAs are MERPs. Health FSAs draw their exclusion from the same section. So does a self-insured medical expense reimbursement plan. Asking “MERP or HRA?” is like asking “vehicle or sedan?”

The full category walkthrough is at What Is a MERP? and the statute underneath it at What Is a Section 105 Plan?

HRA: Employer-Funded, Employer-Owned

A Health Reimbursement Arrangement is funded solely by the employer. Employees cannot contribute, and no salary reduction is involved — which is why an HRA needs no §125 plan to work.

Unused amounts may roll forward if the plan allows, but the money never becomes the employee’s property. It stays with the employer when they leave. The employer sets the annual amount, decides what the arrangement covers within §213(d), and keeps whatever is not claimed.

Established in Revenue Ruling 2002-41 and Notice 2002-45. After the Affordable Care Act, IRS Notice 2013-54 made integration with a group health plan the ordinary route for active employees, with ICHRA and QSEHRA as the defined exceptions.

Health FSA: Employee-Funded, On a Deadline

A health Flexible Spending Arrangement is funded by the employee through a pre-tax salary reduction under §125, up to an annual limit the IRS indexes each year. Employers may contribute but usually do not.

Two features define it in practice. The full annual election is available on day one, before the employee has funded it — the uniform coverage rule, and a real risk the employer carries. And the money is use-it-or-lose-it at year end, softened only if the plan adopts a limited carryover or a grace period. It cannot do both.

A health FSA may not reimburse insurance premiums at all. Proposed Treasury Regulation §1.125-5(k)(4) is categorical: a health FSA is not permitted to treat employees’ premium payments for other health coverage as reimbursable expenses.

Section 125 Is a Mechanism, Not a Benefit

Section 125 is the odd one in the list because it is not a plan that pays for anything. It is the provision that lets an employee choose between taxable cash and a nontaxable benefit without being taxed on having had the choice.

Without §125, constructive receipt would tax an employee who could have taken the cash, whether or not they did. Proposed Treasury Regulation §1.125-1(b)(1) is the provision that suspends that result for a defined menu of qualified benefits. The further step — treating the elected amounts as employer contributions to the accident and health plan — rests on §125 itself and the balance of the 2007 proposed package rather than on that one paragraph, and it is worth having your own advisor confirm the characterization for your plan.

So “Section 125 plan” and “cafeteria plan” describe the wrapper. §105 makes the reimbursement tax-free coming out; §125 makes the contribution pre-tax going in. Your existing pre-tax health insurance deduction already uses both.

HSA: The One That Is Genuinely Different

A Health Savings Account is not a MERP and not an employer plan. It is an individually owned trust account under IRC §223.

It requires enrollment in a qualified high-deductible health plan. The money belongs to the employee permanently, moves with them between jobs, can be invested, and has no deadline. Either party may contribute, within an annual limit the IRS indexes.

That ownership difference is the whole distinction. An HSA is the employee’s asset. An FSA is the employee’s money on a clock. An HRA or other MERP is the employer’s promise to pay for care the employee actually incurs.

Side by Side

Who funds it

HRA: employer only. Health FSA: employee by salary reduction, employer optional. HSA: either. SIMERP: employee salary reduction under §125, treated as an employer contribution for accident and health plan purposes.

Who owns what is left

HRA: employer. Health FSA: forfeited at year end, subject to carryover or grace period. HSA: employee, permanently and portably. SIMERP: not an accumulating balance, so nothing is left to own.

Does it need a Section 125 plan

HRA: no. Health FSA: yes. HSA: not required, but a §125 plan is how most payroll contributions are made pre-tax. SIMERP: yes.

Does it require other coverage

HRA: generally must be integrated with a group plan for active employees, per Notice 2013-54, unless it is an ICHRA or QSEHRA. Health FSA: no. HSA: requires a qualified high-deductible health plan. SIMERP: designed to layer alongside existing coverage rather than replace it.

What it reimburses

All of them are bounded by IRC §213(d). The working list is at IRS Publication 502: What’s Actually Reimbursable. Plan documents may be narrower than the statute; none may be broader.

Can You Have More Than One?

Usually yes, and this is where the real planning happens. The constraints cluster around the HSA, because HSA eligibility is fragile.

HSA plus a general-purpose health FSA: no. A general-purpose FSA is disqualifying coverage, and it disqualifies for the entire plan year, not just the months it is used. A spouse’s general-purpose FSA can disqualify you too.

HSA plus a limited-purpose FSA: yes. A limited-purpose FSA restricted to dental and vision, or a post-deductible FSA, preserves HSA eligibility.

HSA plus an HRA: only if the HRA is limited. A general-purpose HRA is disqualifying. A limited-purpose, post-deductible, retirement or suspended HRA is not.

HRA plus a health FSA: yes. Common, and the plan documents set the ordering — which pays first materially changes the outcome, so it should be deliberate rather than inherited.

HSA plus a SIMERP: ask before you enrol. The same logic that makes a general-purpose HRA disqualifying applies to any arrangement that reimburses general §213(d) care before the deductible is met, and a self-insured medical expense reimbursement plan has to be assessed on its own design against Revenue Ruling 2004-45. Two developments since then may change the answer for plans built around a fixed-fee virtual care clinic: the One, Big, Beautiful Bill Act amended §223 in July 2025, and IRS Notice 2026-5 is the guidance implementing it. If you hold an HSA, put this question to your own advisor and to the plan administrator in writing, and get the answer before you enrol rather than after.

Anyone actually holding two of these should have their specific combination checked by their own advisor. The rules are unforgiving and the penalty for getting HSA eligibility wrong is retroactive.

Which One Fits Your Situation

Stated plainly, without pretending these are interchangeable.

You want to give employees a defined benefit dollar and keep what goes unused: an HRA.

You want employees to fund their own predictable medical costs pre-tax: a health FSA.

You want employees to build a portable asset and you offer a high-deductible plan: an HSA.

You have no group plan and fewer than 50 full-time equivalents: a QSEHRA.

You would rather fund individual market coverage than run a group plan: an ICHRA.

You already have a health plan you are keeping, and the problem is that it costs too much: this is the case none of the above solves, and it is where a SIMERP is aimed.

Where SIMERP Fits

A self-insured medical expense reimbursement plan is a §105(b) plan funded through a §125 election, reimbursing §213(d) medical care delivered by licensed physicians through a virtual care clinic. It layers alongside existing coverage. Nothing about the current plan, network or deductible changes.

What separates it economically from the others on this page is where the money comes from. An HRA or FSA changes the tax treatment of money the employer or employee was already going to spend on care. A SIMERP works on payroll tax — the treatment IRS Publication 15 (Circular E) states in Section 5, grounded in IRC §3121(a)(2). On published figures that averages $640 per enrolled employee per year net of program costs, and it starts on the first payroll run after launch rather than at a plan year boundary.

The employee-side question — whether a pre-tax deduction shrinks the paycheck — is covered on the savings page, which walks the payroll math and the modeled employee example.

Primary Sources

• IRC §105 — the medical reimbursement exclusion and the §105(h) nondiscrimination tests.
• IRC §125 — cafeteria plans and the pre-tax election.
• IRC §213(d) — the definition of medical care.
• IRC §223 — health savings accounts and the high-deductible plan requirement.
• IRC §3121(a)(2) — the payroll-tax wage exclusion.
• Proposed Treasury Regulation §1.125-1(b) — salary reduction treated as employer contribution.
• Revenue Ruling 2002-41 and Notice 2002-45 — HRAs.
• IRS Notice 2013-54 — ACA integration of HRAs.
• Revenue Ruling 2004-45 — the controlling authority for the HSA eligibility interactions above: general-purpose FSAs and HRAs are disqualifying coverage; limited-purpose, post-deductible, retirement and suspended arrangements are not.
• IRS Notice 2026-5 — current guidance on the health savings account changes made by the One, Big, Beautiful Bill Act (Pub. L. 119-21, July 4, 2025). Anything written about HSA eligibility before 2026 should be checked against it.
• IRS Publication 969 — the plain-language companion on HSAs, FSAs, HRAs and MSAs.
• IRS Publication 502 — the medical expense list.

Your Next Step

If the shortlist has narrowed and the question is what the payroll math looks like at your headcount, the Savings Assessment takes three minutes and books your next step on the screen straight after — a 20 minute Discovery Call at 50 or more W-2 employees, or the live group briefing below that.

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