The QBI Deduction: How Business Owners Leave 20% on the Table

The Section 199A deduction lets pass-through owners deduct up to 20% of qualified business income. On $400,000 of QBI, that is an $80,000 deduction, and most owners who lose it lose it to their own income level, entity structure, or payroll choices rather than to the statute.

What Section 199A Actually Does, and Who Can Claim It

The deduction is available to sole proprietors, S-corps, partnerships, and certain LLCs. It applies cleanly to businesses that are not "specified service trades or businesses" (SSTBs), meaning any business whose principal asset is the skill or reputation of its owners: consulting, law, medicine, financial services, and similar fields.

Confirm the exact 2026 thresholds with your CPA, but the structure works like this: below a lower taxable income threshold, SSTB owners qualify for the full deduction. Above an upper threshold, it is gone entirely. In between, it phases out ratably. Non-SSTB owners instead face limits tied to W-2 wages paid and the unadjusted basis of qualified property (UBIA).

Those limits are the piece most owners miss. Once your income clears the lower threshold, your deduction is capped at either 50% of W-2 wages paid by the business, or 25% of W-2 wages plus 2.5% of UBIA, whichever is greater. A profitable S-corp with no employees and few fixed assets can hold a deduction worth almost nothing.

The Planning Levers That Actually Move the Number

Three levers do the real work here.

Retirement-plan contributions. The deduction is calculated against taxable income, not gross revenue. A SEP-IRA, Solo 401(k), or defined benefit contribution reduces your W-2 income and your QBI at once, which can pull taxable income back below a phase-out threshold. A $70,000 Solo 401(k) contribution in the right year can mean keeping a five-figure deduction you would otherwise lose.

Entity structure. An LLC taxed as a sole proprietor with strong profits and no payroll is exposed to the W-2 wage limitation. An S-corp election, sized with a reasonable salary, creates W-2 wages that can unlock a larger deduction. Payroll taxes and overhead mean it does not always pencil out, but it often does, and most owners have never run it.

Income timing. Accelerating deductible expenses, deferring a year-end invoice, or timing a bonus can shift taxable income across a threshold. This is where the Soil layer of the Sporos Doctrine earns its keep, because decisions made in November shape a deduction claimed in April.

The Takeaway

The fact that decides your answer is where your projected taxable income lands relative to the phase-out range, not how profitable the business was. Two SSTB owners on either side of the upper threshold can run identical businesses and claim wildly different deductions.

The expensive version is not neglect. It is owners who do everything right at the return level and still lose the deduction because nobody looked at the number until the books closed. By April the contribution is capped, the invoice recognized, the S-corp election a year too late.

If your income is anywhere within reach of a threshold this year, that is worth a conversation before you close the books.

The information provided is for educational purposes only and does not constitute investment, legal, or tax advice. Consult with qualified professionals for guidance specific to your situation.