A 58-Year-Old Orthodontist Discovers How to Shield $300,000 From Taxes Using a Hidden 401(k) Strategy

A 58-year-old orthodontist pulling roughly $700,000 in profit from a practice with three employees has already maxed a 401(k) and watches another $200,000 fall into the top federal bracket. The standard playbook tops out at the $72,000 combined employee plus employer limit for 2026, leaving a six-figure tax bill that looks permanent but is not.

A cash balance plan layered on top of the 401(k) can absorb another $150,000 to $250,000 in pre-tax dollars every year. For an owner in their late 50s or early 60s, this structure is frequently overlooked or dismissed as too much paperwork. The math is unusually generous: the IRS treats cash balance plans as defined benefit plans, and the funding limit scales with how few years remain until retirement.

Why the Limit Explodes After 50

A cash balance plan is a defined benefit plan structured to resemble a 401(k). Each participant holds a hypothetical account that grows through a pay credit set by the plan document, plus an interest credit often tied to the 10-year Treasury yield. That yield was running around 4.6% as of late July 2026, up from earlier in the year. The IRS caps the maximum annual benefit a participant can receive at $290,000 for 2026, under Section 415(b). To fund that promised benefit across a shrinking number of working years, an actuary backs into a deductible contribution that grows larger the closer the owner is to retirement.

The age-based math is striking. For a 55-year-old, the calculation typically supports a deductible contribution near $200,000. By age 60, it climbs above $260,000. By 65, it can exceed $300,000. An enrolled actuary certifies this figure annually, drawing on the owner’s compensation, age, and the plan’s interest crediting assumption. The IRS compensation limit that applies to these calculations is $360,000 for 2026, and the lifetime lump-sum accumulation cap sits at approximately $3.7 million.

Stacking the Two Plans

The cash balance plan sits on top of the 401(k). A typical stack for a 58-year-old owner looks like this:

1. 401(k) employee deferral. The 2026 base limit is $24,500, plus the age-50 catch-up of $8,000, for $32,500 total. Owners who earned more than $150,000 in 2025 must route that catch-up to a Roth 401(k) under the SECURE 2.0 rule, which took effect January 1, 2026. The IRS issued final regulations with a good-faith compliance standard available through 2026, so the upfront pre-tax deduction shrinks to $24,500 for high earners making Roth catch-up contributions.
2. Profit sharing contribution. The employer side fills the rest of the $72,000 combined limit, typically around $46,500 for an owner taking the full salary deferral. This piece is fully deductible to the business. Note that when pairing a cash balance plan with a 401(k), the IRS generally limits profit sharing to 6% of covered compensation rather than the full ceiling.
3. Cash balance contribution. A separately deductible defined benefit contribution, sized by the actuary. For a 58-year-old earning $345,000 or more in W-2 wages, a contribution of $200,000 is realistic.

Add the three buckets and the owner has shielded close to $300,000 from current taxes. At a 37% federal marginal rate plus state, the first-year cash savings can approach $120,000.

The Catches Worth Knowing

Employees must be funded too. A cash balance plan has to satisfy IRS nondiscrimination testing, which typically requires contributing 5% to 8% of pay for staff. For a practice with three employees earning $60,000 each, that runs roughly $12,000 a year. The owner’s tax savings still dwarf the employee cost, but the plan only makes sense when an older, higher-paid owner works alongside a younger, lower-paid workforce.

The plan also demands a real commitment. The IRS expects contributions for at least three to five years. Skipping a year without formally amending the plan triggers excise taxes. The current 10-year Treasury environment, with yields in the 4.6% range, matters because the interest crediting assumption directly shapes how much can be contributed each year. Lower rates historically allow higher contributions, while the relative stability seen in mid-2026 has kept the actuarial math predictable for most plan sponsors.

What to Do Before Year-End

1. Run a feasibility study. A third-party actuary will model your exact deductible contribution based on W-2 income, age, and employee census. Most firms provide this analysis at no cost as part of winning the design work.
2. Adopt the plan by December 31. A cash balance plan must be in place by the last day of the fiscal year to generate a deduction for that year. The funding itself can wait until the tax filing deadline, including extensions.
3. Coordinate the 401(k) restatement. Pairing the two plans requires amending the 401(k) to a safe harbor design and realigning employee contributions to satisfy combined nondiscrimination testing. Skipping this step is the most common reason cash balance plans fail an audit.

For an owner staring at a $200,000 tax bill on the last slice of profit, this is the single largest legal deduction the tax code still offers high earners. The window to use it for 2026 closes December 31.

Editor’s note: This article was updated to reflect the current 10-year Treasury yield of approximately 4.6% as of late July 2026, the 2026 IRS Section 415(b) defined benefit annual benefit cap of $290,000, the $360,000 compensation limit, the $3.7 million lifetime lump-sum cap for cash balance plans, and the SECURE 2.0 Roth catch-up effective date of January 1, 2026, with a good-faith compliance standard available through the end of the year under the IRS final regulations.

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