Twenty percent of qualified business income sounds like a number that should always be at least something. It is entirely possible for the actual deduction to be $0, or a small fraction of that 20% figure, and for that to be the statute working exactly as written rather than a mistake in a calculation. There are three distinct reasons this happens, and they call for different responses.
| Reason | What triggers it | Is it really $0, or partial? |
|---|---|---|
| Specified service business (SSTB), above the phase-in range | Taxable income is above the threshold-plus-range for your filing status, and the business is health, law, accounting, consulting, financial services, performing arts, athletics, or another field the statute names, or its principal asset is an owner's or employee's reputation or skill. | Exactly $0 from that business. There is no floor -- the SSTB reduction reaches 100% at the top of the range and does not partially apply above it. |
| W-2 wage / UBIA limit, no SSTB | Taxable income is above the threshold-plus-range, the business is not an SSTB, and it paid little or no W-2 wages and holds little or no depreciable qualified property (UBIA). | Capped at the greater of 50% of wages or 25% of wages plus 2.5% of UBIA -- both near $0 if wages and UBIA are near $0, even though 20% of QBI itself might be large. |
| Negative QBI | The business's qualified business income for the year is negative -- possible even in a year with positive cash flow, once startup costs, Section 179, or a loss year's ordinary business deductions are counted. | $0 for this business this year. The negative amount carries forward and reduces next year's QBI from the same business instead. |
Above the top of the taxable-income phase-in range for your filing status, a specified service trade or business (SSTB) -- health, law, accounting, consulting, financial services, performing arts, athletics, or a business whose principal asset is an owner's or employee's reputation or skill -- gets $0 of QBI deduction from that business, full stop. There is no partial amount above the range; the SSTB reduction reaches 100% exactly at the top of the range and stays there.
Above the phase-in range, a non-SSTB's deduction from a business is capped at the greater of 50% of that business's W-2 wages, or 25% of W-2 wages plus 2.5% of the UBIA of its qualified property. A sole proprietor with no employees and no significant depreciable equipment can have both figures at or near $0, which caps the deduction at or near $0 even though the business is not an SSTB and 20% of QBI would otherwise be a large number.
Check whether QBI itself, not the deduction, is negative. Qualified business income is not simply revenue -- it is the net amount of income, gain, deduction, and loss from the business, so a year with heavy startup costs, a large Section 179 deduction, or a bad stretch can produce negative QBI even when cash flow was positive. Negative QBI produces a $0 deduction for that business this year and instead reduces the QBI that same business reports next year.
Only in narrow cases, and only for 2026 and later. The One Big Beautiful Bill Act's $400 minimum deduction requires at least $1,000 of QBI from an active qualified trade or business, and it is layered on top of the SSTB and wage/UBIA rules, not a replacement for them -- it raises a small positive result up to $400, it does not turn a $0 SSTB result above the range, or a $0 result from negative QBI, into something positive.
Run your numbers through the calculator this page links to. It reports which limitation applied -- SSTB fully phased out, wage/UBIA limit, negative QBI carryforward, or none -- as a labeled finding alongside the dollar result, rather than just a final number with no explanation of why it is small.