Cash Balance Plans for Law Firm Partners: The Tax Shelter Beyond the 401(k)

An equity partner at an AmLaw 100 firm netting $700K last year saved $56,500 in the firm's 401(k) plan. Her 54-year-old colleague across the hall sheltered $247,000 — including $175,000 in a cash balance plan she added two years ago. Same income. Same firm. The difference: a defined benefit plan that most Big Law partners have never been told about.

What a cash balance plan is

A cash balance plan is a type of defined benefit (DB) pension plan — but it looks and behaves more like a 401(k) than a traditional pension. Instead of promising a monthly benefit at retirement, a cash balance plan maintains a hypothetical "account balance" for each participant. Each year, the employer contributes a "pay credit" (a percentage of compensation or a flat dollar amount), and the account earns a stated "interest credit" defined in the plan document — typically a fixed rate (e.g., 4–5%) or an index-tied rate.

At retirement, the participant takes the accumulated balance as a lump sum or annuity. The plan sponsor (the law firm or your professional corporation) makes the annual contributions and deducts them currently. The IRS regulates the maximum annual benefit that can be funded under Section 415(b) — and in 2026, that limit is $290,000 per year.¹

Why equity partners are the ideal candidate

Cash balance plans work best for high-income individuals who are: (1) over 40, (2) earning consistently high income, and (3) want to reduce current taxable income aggressively. Law firm equity partners check every box.

The reason age matters: a cash balance plan targets a fixed account balance at retirement age (typically 62 or 65). The fewer years until retirement, the more the plan must contribute each year to fund that target — which means older partners can put in dramatically more per year, up to the §415(b) limit.

2026 contribution limits and age-based ranges

Unlike a 401(k) with a flat dollar limit, cash balance contributions are actuarially calculated. The §415(b) limit ($290,000 for 2026) caps the maximum annual benefit payable at normal retirement age — contributions are whatever is actuarially required to fund that benefit over your working years. This is why older partners can contribute so much more per year.

Contribution ranges are approximate and depend on plan design, compensation history, and actuarial assumptions. Your plan actuary sets the annual required contribution. Federal tax savings shown at 37% marginal rate; state savings additional.

Stacking a cash balance plan with your 401(k)

The most powerful aspect of a cash balance plan is that it is a separate plan from the 401(k)/profit-sharing plan. The contribution limits don't merge. A 52-year-old equity partner in 2026 can combine both:

Compare this to the 401(k)-only scenario: $72,000 sheltered, $26,640 in federal tax savings. The cash balance plan multiplies the shelter by more than 3×.

The contributions are also deductible at the entity level — meaning they reduce the law firm's (or your PC's) taxable income before calculating SE tax. For partners in the 37% bracket with 3.8% NIIT exposure on top, the effective combined marginal rate on sheltered income can exceed 42% federally before state taxes. The cash balance deduction is worth significantly more per dollar than ordinary business deductions that only reduce income tax.

Law firm structure: the critical variable

The biggest practical hurdle for Big Law partners is that most law firms are organized as large multi-party partnerships or LLPs. Setting up a retirement plan at the firm level means covering all eligible employees — partners and associates. At a 200-attorney firm, funding a cash balance plan for every associate earning $225K+ would cost millions and eliminate the economics for the partners.

There are several ways around this, depending on your specific situation:

1. You work through a professional corporation (PC)

Some partners, particularly those in professional corporations or LLCs wholly owned by the partner, can sponsor their own defined benefit plan independent of the law firm. The PC is the employer. If the PC has no W-2 employees other than the partner and perhaps their spouse, the plan doesn't need to cover anyone else. This is the cleanest structure and the most common setup for high-income solo practitioners and small boutique partners.

2. The firm sponsors a partner-only plan

Some law firms — particularly smaller firms with 5–30 partners and limited associate headcount — sponsor cash balance plans that cover partners only. This is possible when the plan uses age and service requirements that effectively exclude younger associates by design (not by exclusion), and the plan passes IRS nondiscrimination testing. This requires an experienced actuary and ERISA counsel. AmLaw 200 firms rarely do this because of the associate coverage cost; boutique firms do it regularly.

3. You're at a firm that already offers one

A small but growing number of AmLaw 200 firms have added cash balance plans for partners as a retention and compensation tool. If your firm has one, the contributions are managed by the plan actuary — your role is to understand what's being contributed on your behalf and how it affects your overall retirement picture.

4. You're transitioning to a smaller firm or going of counsel

Partners moving to a 10-partner boutique, going of counsel to a smaller firm, or starting their own practice are often the best candidates to establish a new cash balance plan. The setup cost ($1,500–$3,000 for plan documents plus annual actuarial fees of $2,500–$5,000) is economically trivial relative to the six-figure annual tax savings.

When a cash balance plan makes sense — and when it doesn't

Interaction with NQDC distributions and IRMAA

One nuance equity partners often miss: cash balance plan distributions at retirement are taxable as ordinary income and add to the IRMAA income calculation for Medicare premiums. If you're already planning large NQDC distributions in the same years as cash balance draws, you could face significant IRMAA surcharges — potentially $6,000–$10,000+ in additional Medicare premiums per year per person — on top of regular income tax.

This is where the retirement sequencing analysis matters. An advisor who understands your full retirement income stack — Social Security timing, NQDC distribution elections, capital account return schedule, cash balance distributions, and taxable account draws — can design a sequence that minimizes IRMAA, avoids Roth conversion windows being crowded out, and spreads income more evenly across your retirement years.

Implementation timeline and next steps

A cash balance plan for a professional corporation or small firm follows this general timeline:

• October – November: Engage an actuary and ERISA plan attorney. Design the plan — benefit formula, interest credit rate, normal retirement age, and vesting schedule.
• December 31: Plan must be adopted (signed plan document) by December 31 of the tax year for contributions to be deductible in that year. This is a hard deadline.
• March 15 (or September 15 with extension): Last day to make the annual cash balance contribution and still deduct it on the prior-year tax return for partnerships and S-corps.
• Annual: Actuary certifies the required contribution. You fund the plan by the deadline. Form 5500 filed annually (Form 5500-EZ for single-participant plans).

If you are considering a 2026 plan, the deadline to adopt it is December 31, 2026. The practical deadline to engage an actuary and get documents finalized is October–November 2026 — actuaries are heavily backlogged in December.