Tax

The Solo Practitioner Retirement Stack: 401(k) + Cash Balance + DB

How high-income solo physicians, lawyers, and dentists combine multiple plans to shelter $300K+/year. The full stack with sequencing and trade-offs.

By Aparna Devalla, CPA3 min · 5 slidesUpdated June 15, 2026

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Single retirement plan caps don't reflect what high-income solo professionals can actually shelter.
Solo 401(k): up to $69K (2024 limit) with employee + employer.
Cash balance or defined benefit plan: stacked ON TOP of the 401(k), $100K–$250K additional shelter depending on age and comp.
Combined: $150K–$320K+ of tax-deferred shelter annually.
At top federal + state marginal rates, that's $60K–$130K+ of annual tax savings.

Hypothetical individual accounts with annual pay credits and interest credits.
Contribution capacity scales with age: a 55-year-old can credit dramatically more than a 35-year-old.
Typical contribution: $100K–$200K/year for owner-only plans at ages 45+.
Requires annual actuarial valuation ($3K–$5K).
Combined with Solo 401(k): the 401(k) handles employee deferral; the cash balance plan layers profit-share+ on top.

Promise of a specified retirement benefit (e.g., 100% of comp at retirement).
Required funding calculated annually by actuary to meet projected benefit.
Older participants (50+) get dramatically higher contributions than younger.
Pure DB plans are less common than cash balance in solo settings — but for the right facts, they shelter even more.
Annual administrative cost: $4K–$8K including actuary, custodian, TPA.

Step 1: max Solo 401(k) employee deferral ($23K).
Step 2: optimize Solo 401(k) employer profit-share within the combined $69K cap.
Step 3: layer cash balance OR defined benefit plan on top (subject to combined annual contribution limit rules).
Step 4: model the 415(c) and PBGC limits — high contributions face deduction limit and benefit accrual rules.
Best fit: solo professional with stable $400K+ annual income, age 45+, committed to multi-year contributions.
Need help architecting the full retirement stack? Rubric Financial coordinates plan selection, TPA, and ongoing administration for solo high-income professionals.

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