Section 199A QBI Deduction for Law Firm Partners: Who Gets It, Who Doesn't, and How to Plan (2026)

The fundamental problem: law firms are SSTBs

Section 199A of the Internal Revenue Code allows qualifying business owners to deduct 20% of their qualified business income (QBI) from taxable income — potentially worth $50,000+ per year to a high-income professional. For S-corp owners and sole proprietors in most industries, this deduction phases out based only on W-2 wages and capital. For law firm equity partners, there is an additional obstacle: law is specifically listed as a specified service trade or business (SSTB).¹

SSTBs face a hard phase-out: once taxable income exceeds the upper threshold, the deduction is eliminated entirely — regardless of W-2 wages or invested capital. There is no workaround at the entity level. A law firm cannot restructure to escape SSTB classification. The only path to a §199A deduction is to have taxable income below the phase-out ceiling.

2026 phase-out thresholds: OBBBA expanded the window

The One Big Beautiful Bill Act (signed July 4, 2025) made §199A permanent and expanded the SSTB phase-out windows starting in tax year 2026. Here are the current thresholds:²

For pre-OBBBA tax years (2018–2025), the phase-out window was $50,000 (single) / $100,000 (MFJ). The OBBBA expanded these to $75,000 / $150,000 — meaning more partners whose income falls in the partial-deduction zone can now take a meaningful deduction instead of facing abrupt cutoff. The effect is most significant for mid-size firm partners in the $225,000–$275,000 (single) or $440,000–$550,000 (MFJ) range.

Taxable income for this test is calculated before the §199A deduction itself.

Reality check: what this means for BigLaw partners

For most equity partners at AmLaw 200 firms, the §199A deduction is $0. A third-year equity partner at a mid-tier BigLaw firm with $600,000 of K-1 income — below the median PEP at most AmLaw 100 firms — is already above both the single and MFJ upper thresholds. A first-year equity partner at Kirkland or Wachtell earning $1M–$3M+ sees no benefit.

If you are a BigLaw equity partner earning above $553,500 MFJ or $276,775 single, stop reading about the deduction and start reading about planning strategies — the only way you benefit is by reducing taxable income below the threshold.

§199A calculator for law firm equity partners

Enter your taxable income (before the §199A deduction) and your allocable share of the firm's QBI. For equity partners, QBI is your K-1 Box 1 ordinary income less any guaranteed payments and deductible items allocable to the business. If taxable income exceeds the upper threshold, the result is $0.

How the phase-out math works

For SSTBs within the phase-out range, the available QBI itself phases to zero — not just the deduction rate. The IRS calls this the "applicable percentage" approach:

For SSTBs above the upper threshold, there is no W-2 wage or capital-based workaround. The phase-out eliminates the SSTB allocation entirely before the W-2/UBIA limitation would even apply. This differs from non-SSTB pass-through businesses, where owners above the threshold can still qualify if they pay sufficient W-2 wages.

Non-equity partners: guaranteed payments are not QBI

Income partners (non-equity partners) and lawyers receiving guaranteed payments under IRC §707(c) face a structural barrier that is separate from the income threshold. Guaranteed payments are explicitly excluded from the recipient's QBI.³ They reduce the partnership's QBI, but the individual recipient treats them as ordinary W-2-equivalent income — no pass-through business deduction applies.

In practice, this means:

• An income partner earning $250,000 in guaranteed payments and nothing else gets a §199A deduction of $0 — even if that income is below the single-filer threshold.
• An equity partner whose draw structure blends guaranteed payments with distributive share allocations must identify which portion flows through as true QBI on their K-1 Box 20 (Code Z) before calculating any deduction.
• A boutique equity partner with a small guaranteed-payment component can still claim the deduction on the distributive-share portion, if that portion is below the threshold.

Planning strategies: how to access the deduction

For equity partners above the threshold, the only lever is reducing taxable income below the phase-out ceiling. The most effective tools are pre-tax retirement plan contributions, which reduce W-2 income and K-1 allocations simultaneously:

1. Cash balance plan + 401(k) stacking

A defined-benefit cash balance plan layered over a solo 401(k) can generate contributions of $100,000–$350,000 per year depending on age, more than enough to move a mid-tier equity partner below the $403,500 MFJ threshold. The combined retirement deduction reduces the K-1 allocation flowing to the partner's return.

Example: A 52-year-old equity partner filing MFJ with $580,000 of K-1 income adds a cash balance plan ($200,000 contribution, age-based) plus a 401(k) deferral ($32,500, including $8,000 catch-up). Taxable income drops from $580,000 to roughly $347,500 — now inside the MFJ phase-out range with a partial §199A deduction of approximately $11,000, saving ~$4,000 in federal taxes. Not transformative, but worth capturing as part of a broader retirement plan strategy.

2. NQDC deferral elections

Deferring current-year distributions into a firm NQDC plan reduces the taxable K-1 income in the election year. Unlike retirement plan contributions, there is no annual cap limit — a partner could theoretically defer enough to drop below either threshold. The trade-off is counterparty risk (the deferred balance is an unsecured firm obligation) and the §409A constraints on distribution timing. For a partner planning a near-term departure or firm transition, NQDC deferrals are usually the wrong tool to optimize §199A.

3. Charitable bunching and donor-advised funds

Charitable deductions reduce AGI in the year of contribution and lower taxable income toward the §199A phase-out threshold. Bunching two or three years of charitable giving into a single DAF contribution in a high-income year can produce a deduction large enough to shift a partner from above-threshold to within the partial-deduction zone. The OBBBA added a 0.5% AGI floor and a 35% deduction cap for 37%-bracket filers on cash donations — appreciated-security donations to DAFs are unaffected by those limits and remain fully deductible at fair market value.

4. For partners near the MFJ threshold: spousal income matters

The §199A phase-out uses combined household taxable income on a MFJ return. A partner with $350,000 of QBI (below the single threshold) who files MFJ with a spouse earning $100,000 may find that combined income of $450,000 pushes them into the MFJ partial phase-out range. Conversely, a partner above the single threshold who files MFJ may stay below the MFJ threshold if spousal income is low. This makes filing status analysis a part of §199A planning for married equity partners.

OBBBA changes effective 2026: what actually changed

The expanded phase-out window is the most practically significant change for equity partners near the threshold. In 2025, a single filer at $240,000 would have been 99% phased out; in 2026 the same filer is only 51% phased out and retains nearly half the potential deduction. Partners in the $200K–$275K range (single) or $400K–$550K range (MFJ) should recalculate their §199A position for 2026 — the deduction may be substantially larger than in prior years.

Working with an advisor on §199A

The §199A analysis for a BigLaw equity partner sits at the intersection of partnership tax, compensation planning, and retirement plan design. Most generalist advisors do not model it as part of a holistic plan. Key questions to bring to an advisor:

• Does my current retirement plan stack (401k + cash balance) reduce my K-1 allocation enough to move me into or below the phase-out range?
• How does my spouse's income interact with the MFJ threshold, and should we model filing status?
• If I lateral to a smaller firm with lower income, does §199A open up materially?
• Are my guaranteed payments properly identified and excluded from QBI on my K-1?
• If I am transitioning to of-counsel or winding down my practice, is there a year where retirement plan contributions could make the §199A deduction available?