Tax Strategy for Law Firm Owners: Retirement Plans and Entity Moves That Actually Move the Needle

She built a boutique law practice in San Diego over twelve years. Nine attorneys, two paralegals, $1.8 million in revenue. The retirement plan has been the same solo 401(k) she opened when she was the only lawyer in the room. Every year she maxes it at $23,500, plus the $7,500 catch-up now that she is over 50. Every April she files her return and writes a check for more than $80,000, wondering why a practice this profitable still leaves her in the same spot.

She is not alone. Most law firm owners treat retirement funding and entity structure as one-time decisions made years ago and never revisited. But the practice has grown, the income has climbed, and the ceiling she is bumping against is not the IRS. It is a plan that was designed for a smaller firm.

The retirement ceiling most law firm owners hit

A solo 401(k) or a SEP IRA is the default choice for most legal professionals. They are easy to set up, carry low administrative overhead, and work fine at lower income levels. At $300,000 or more in practice income, they stop working well.

The solo 401(k) caps employee deferrals at $23,500 for 2026, plus $7,500 if you are 50 or older. On top of that, the business can make a profit-sharing contribution of up to 25% of compensation. For an S corp owner paying herself a $200,000 salary, that profit share caps around $50,000. Total: roughly $81,000 in annual contributions. That is better than the standard 401(k) most employees get, but it still leaves a partner clearing $600,000 or more with a tax bill that dwarfs what she sheltered.

The SEP IRA is even more constrained for owners with employees. Every dollar you contribute for yourself must be matched as a percentage for every eligible employee. At a nine-attorney firm, that cost multiplies fast enough that many owners never fund the SEP to its full limit.

Neither plan was built for a practice that crosses half a million in profit.

When a cash balance plan changes the math

A defined benefit plan — often structured as a cash balance plan — is the tool that changes the ceiling entirely. Unlike a 401(k), where the contribution limit is a fixed dollar amount, a cash balance plan lets the firm contribute whatever is actuarially needed to fund a promised benefit at retirement. For an owner in her mid 50s, that can mean sheltering $150,000 to $200,000 or more per year above and beyond the 401(k) deferral.

Here is how it works in practice. The plan sets a hypothetical account balance for each participant. The firm contributes enough each year to meet the target. Those contributions are tax deductible to the firm and grow tax deferred inside the plan. The contribution level is tied to age — older owners can fund more because they have fewer years until retirement — which makes cash balance plans especially effective for partners in their late 40s and 50s.

A solo practitioner or a small firm with no employees under 40 can tilt the plan heavily toward the senior partners. A firm with a younger staff needs to account for their benefit accruals too, which is why the design phase matters. A well-structured plan layers the cash balance contributions on top of an existing 401(k) profit-sharing arrangement, so the firm continues to fund the base retirement plan for all employees while the partners capture the additional tax-deferred room.

Entity choice matters for retirement

The type of entity your practice runs through determines which retirement plans are available and how the contribution math works. A firm operating as a sole proprietorship or a single-member PLLC files retirement contributions against the owner's personal return. An S corp or a PC files them through payroll, which changes the basis for the profit-sharing calculation.

The choice between a PLLC and an S corp is often discussed only in terms of self-employment tax savings, but it has an equally important effect on retirement plan capacity. Under an S corp, the owner's compensation must be reasonable — not artificially low — because the profit-sharing contribution is calculated as a percentage of that salary. An owner who set her salary at $60,000 to minimize payroll tax has also capped her profit-sharing contribution at roughly $15,000. A salary of $200,000 unlocks $50,000 in profit-sharing room.

The same logic applies to multi-entity structures. A firm that owns its building through a separate entity, or that has a side practice with its own retirement plan, needs to coordinate the contribution limits across all plans. Separate entities do not mean separate limits. The IRS aggregates all plans the owner is associated with.

How multi-attorney firms stack plans

A law firm with multiple partners has more flexibility than a solo practice, not less. Each partner can participate in the same firm-wide cash balance plan, with benefit targets set individually based on age and compensation. A 58-year-old partner can fund $200,000 while a 42-year-old partner funds $80,000, all within the same plan document.

The key is coordinating the plan design so that the older partners are not capped by the younger ones' participation limits. An experienced third-party administrator who works with professional firms can structure the benefit tiers so the plan is cost-effective for the firm while the senior partners capture most of the tax-deferred room. The firm also keeps its existing 401(k) profit-sharing plan in place for all employees, which satisfies the coverage testing rules.

Timing the moves before year end

A cash balance plan must be adopted before the end of the tax year to deduct contributions for that year. For a calendar-year firm, that means the plan document needs to be signed by December 31. The funding can happen after year end, as late as the tax filing deadline including extensions, but the plan itself must exist on the books before the year closes.

That makes Q4 the window for law firm owners who want to add a cash balance plan for the current tax year. The same timeline applies to switching entity types — an S corp election for the following year must be filed by March 15, but planning the change starts months earlier.

Most firms that wait until April to look at their tax situation have already missed the deadline for the most impactful moves. A year-round planning relationship catches those windows while they are still open.

FAQ

What is the best retirement plan for small business owners?

For law firm owners earning $300,000 or more, a combination of a solo 401(k) or safe harbor 401(k) with profit sharing, paired with a cash balance plan, offers the highest contribution limits. The exact structure depends on the firm's entity type and how many employees participate.

What are the best retirement options for S-Corp owners?

S corp owners can adopt a solo 401(k) with profit sharing, a SEP IRA, or a cash balance plan. The cash balance plan typically offers the highest contribution potential for owners in their 40s and 50s, because it is based on actuarial targets rather than fixed dollar limits.

What are the best retirement plans for LLC owners?

LLC owners filing as sole proprietors or single-member LLCs have access to the same plans as S corp owners, but the contribution math works differently because there is no separate salary. A solo 401(k) with profit sharing is the most common starting point, with a cash balance plan added once the practice crosses roughly $300,000 in profit.

What's the difference between a CPA and a tax strategist?

A CPA typically prepares returns and may offer tax planning as a secondary service. A tax strategist designs outcomes before the year closes — choosing entity structures, retirement plans, and timing strategies that a return preparer never touches. Law firm owners who work with a strategist start the year knowing where their tax bill is heading.

When should you hire a tax strategist?

The right time is before the fourth quarter, when most year-end planning windows are still open. A strategist can review entity structure, retirement plan capacity, and projected income to recommend changes for the current tax year. The alternative is waiting until April and filing whatever happened.