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 single structure often goes unheard of or dismissed as paperwork. The math is unusually generous because 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 like a 401(k). Each participant has a hypothetical account that grows by a pay credit (set by the plan document) plus an interest credit, often tied to the 10-year Treasury yield, currently around 4.5%. The maximum lifetime benefit the IRS allows works out to roughly a $290,000 annual pension at age 62. To fund that promise across a shrinking number of working years, the actuary backs into a deductible contribution that gets larger the closer the owner is to retirement age.

For a 55-year-old, that calculation typically supports a deductible contribution near $200,000. By age 60, it climbs above $260,000. By 65, north of $300,000. An enrolled actuary certifies this annually based on the owner’s compensation, age, and the plan’s interest crediting assumption.

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 new SECURE 2.0 rule, so the upfront deduction shrinks to $24,500.
2. Profit sharing contribution. The employer side fills the rest of the $72,000 combined limit, usually around $46,500 for an owner taking the full salary deferral. This piece is fully deductible to the business.
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, $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 cash savings in year one approach $120,000.

The Catches Worth Knowing

Employees have to be funded too. A cash balance plan must satisfy IRS nondiscrimination testing, which typically means contributing 5% to 8% of pay to staff. For a practice with three employees earning $60,000 each, that is 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 requires a commitment. The IRS expects contributions for at least three to five years. Skipping a year without amending the plan triggers excise taxes. The 4.5% Treasury environment matters because the interest credit eats into how much can be funded each year. Lower rates allow higher contributions; recent stability has kept the math predictable.

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 do this at no cost to win 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 deduct contributions for that year, although funding itself can wait until the tax filing deadline plus extensions.
3. Coordinate the 401(k) restatement. Pairing the two plans requires amending the 401(k) to a safe harbor design and shifting employee contributions to satisfy combined testing. Skipping this step is the most common reason cash balance plans fail 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 code still offers. The window to use it for 2026 closes December 31.