Medical Practice C-Corp Conversion with Retirement Plan Stacking

The Problem

The practice owner was a board-certified orthopedic surgeon operating through an S-Corporation. With $2.5 million in annual collections and roughly $680,000 in owner compensation, the entire pass-through income was being taxed at the highest marginal rates. The owner was 52 years old and wanted to accelerate retirement savings but was already maxing out a standard 401(k) plan.

The practice employed 8 staff members, and the owner was absorbing significant personal costs for health insurance, continuing medical education, and professional development without any tax-efficient reimbursement structure. Their prior advisor had never modeled the C-Corp election or explored defined benefit plan stacking.

Additionally, the practice was paying for employee health insurance but had not structured it through a Section 105/106 plan, missing opportunities for tax-free fringe benefit treatment.

AE Tax Strategy

1. S-Corp to C-Corp Election Under IRC §1362(d)

After modeling the complete tax picture, we revoked the S-Corp election under IRC §1362(d) and converted the practice to a C-Corporation. At the flat 21% C-Corp rate under IRC §11(b), retained earnings used for practice growth, equipment purchases, and reserves would be taxed at 21% instead of the owner's 37% marginal rate. We structured compensation to retain approximately $180,000 inside the corporation annually, producing a rate arbitrage savings of approximately $28,800 per year.

2. Defined Benefit Plan Stacking Under IRC §401(a) and §404(a)(7)

We implemented a combined defined benefit and 401(k) plan under IRC §401(a) with coordinated contribution limits under IRC §404(a)(7). The defined benefit plan allowed annual contributions of approximately $185,000 based on the owner's age and target benefit, while the 401(k) added another $23,500 in employee deferrals plus employer match. Total sheltered income exceeded $215,000, producing federal income tax savings of approximately $42,000.

3. Health Reimbursement and Fringe Benefits Under IRC §105, §106, §79, §127, and §132

We restructured employee health benefits through a Section 105/106 health reimbursement arrangement, added group term life insurance under IRC §79, an educational assistance program under IRC §127, and qualified employee discounts under IRC §132. For the owner, the C-Corp structure allowed full deduction of health insurance premiums as a corporate expense rather than as an above-the-line personal deduction, and education costs for CME became fully deductible fringe benefits. Combined additional savings: approximately $18,200.

Before & After Comparison

*After column reflects tax benefit value, not tax paid.

Key Takeaways

• C-Corp conversion is not always the right move, but for high-income practice owners who can retain earnings and layer fringe benefits, the math often favors it over S-Corp pass-through taxation.
• Defined benefit plan stacking under IRC §404(a)(7) allows contributions far exceeding standard 401(k) limits — particularly valuable for owners over 50.
• Fringe benefits available exclusively to C-Corp shareholder-employees (health insurance, education, group life) create tax-free compensation that S-Corp 2% shareholders cannot access on the same terms.
• The C-Corp election must be modeled against the full picture including state taxes, potential double taxation on dividends, and the owner's exit timeline.