The Big Beautiful Tax Bill, which the U.S. Congress is currently working to pass, changes the popular Section 199A deduction. At this point, whether the House’s new, tweaked Big Beautiful Section 199A deduction becomes law or not? An open question.
But so you can plan how this new deduction will work in your situation? This short blog post explains the mechanics.
To give you a big picture overview here at the very start? The two main features of the new deduction formula are (1) the tax savings are a little bigger. And then (2) for business owners with limited deductions due to W-2 wages or status as a specified service trade or business, the limitations phase-out more slowly.
The actionable insight here: If the law passes, you want to verify your now larger and better Section 199A deductions are optimized.
New Formula Applies to Tax Years Starting in 2026
A first important note? The Big Beautiful Section 199A deduction applies for tax years beginning after December 31, 2025.
Also, the new Section 199A deduction is permanent. (The current version essentially expires at the end of 2025.)
Percentage Bumps Up from 20 Percent to 23 Percent
The deduction percentage rises from 20 percent to 23 percent.
Example 1: The original Section 199A deduction formula gave a taxpayer with $1,000,000 of qualified business income a $200,000 deduction (potentially.) The big beautiful Section 199A deduction gives that taxpayer a $230,000 deduction (again potentially.)
Note: A limitation exists for both the original and the new version of the Section 199A deduction. Taxpayers get that 20 percent or 23 percentage deduction on the lessor of their qualified business income or on their ordinary (so not long-term capital gains or qualified dividend) taxable income.
Limitations Phase-in Differently
Both the original and new version of the Section 199A deduction limit the deduction for taxpayers with taxable incomes above a threshold amount based on W-2 wages, the unadjusted (before depreciation) basis of depreciable property, and then based on the trade or business falling into a specified service trade or business category like healthcare, law, consulting, and so forth. (People call these SSTBs.)
But the new law changes the “speed” at which the limitations occur. This decreases the marginal tax rate these limited taxpayers pay. (Under the current formula, the marginal tax rate in worst case situations can approach 70 percent.) Mechanically, how this works is confusing. But essentially taxpayers calculate two Section 199A deduction amounts and then use the smaller amount as their tentative deduction.
Note: We’ve got a simple JavaScript calculator here, “The Big Beautiful Section 199A Calculator,” which you can use to make the calculations. But maybe finish reading this post so you understand what’s going on with the formulas.
Step 1 in New Section 199A Limitation Calculation
The first step in determining the Section 199A deduction? The formula calculates the Section 199A deduction looking just at the non-SSTB qualified business income.
It calculates this first potential Section 199A deduction as the lessor of 23 percent of either the qualified business income or as a “limited” amount based on the W-2 wages and original cost of depreciable property. (This is the same formula as in the original version of Section 199A. The formula limits the deduction to the greater of either 50 percent of the business’s W-2 wages or 25 percent of the W-2 wages plus 2.5 percent of business’s depreciable property using the unadjusted basis immediately after acquisition). But let’s work through an actual example.
Example 2: Thomas, a single taxpayer, owns two businesses which each make a $1,000,000 a year: a farm and a law firm. The farm pays $300,000 of wages and uses $400,000 of depreciable machinery. Thus, the first version of the formula ignores the law firm because it’s a specified service trade or business. It only calculates the Section 199A deduction on the farm. This non-SSTB deduction equals the lesser of either 23 percent of the $1,000,000 of qualified business income ($230,000)… or the greater of 50 percent of the wages ($150,000) or 25 percent of the wages ($75,000) plus 2.5 percent of the $400,000 of machinery ($10,000) so $85,000 in total. Thus, the non-SSTB Section 199A deduction equals $150,000.
Step 2 in New Section 199A Limitation Calculation
The second step in determining the new Section 199A deduction works like this. The formula tentatively calculates the Section 199A deduction as equal to 23 percent of all the qualified business income from both non-SSTBs and SSTBs. Then this version of the formula limits this deduction if a taxpayer’s taxable income rises above a threshold amount. Specifically, the formula subtracts an adjustment equal to 75 percent of the amount by which taxable income exceeds the Section 199A phase-out threshold.
In 2025—so the year before the Big Beautiful Section 199A deduction takes effect—the threshold amount equals $197,300 for single filers and $394,600 for married filers. Roughly then, in 2026, the threshold amounts should equal $200,000 for single filers and $400,000 for married filers. (If the Big Beautiful Tax Bill passes, Treasury will probably provide the actual 2026 threshold numbers in late 2025.) But let’s just work through an example using my guesses as to next year’s threshold amounts.
Example 3: Again, Thomas owns two businesses, a farm and a law firm. Both make $1,000,000 a year. Th second version of the Section 199A deduction therefore equals 23 percent of the $1,000,000 of farm income ($230,000) plus 23 percent of $1,000,000 of law firm income ($230,000)… so that’s $460,000… thenthe formula subtracts 75 percent of the taxable income Thomas earns in excess of the single filer’s threshold. If that threshold equals $200,000 and his taxable income equals $1,000,000 due to other deductions he claims? The excess equals $800,000, calculated as the $1,000,000 minus the $200,000. The adjustment amount then equals 75 percent of $800,000 excess, or $600,000. That $600,000 adjustment in effect zeros out the second version of Section 199A deduction which equaled $460,000.
In the end, the limited big beautiful Section 199A deduction then equals the greater of the two version’s calculation results: $150,000 or $0. And that means a Section 199A deduction equal to $150,000.
Business Development Company Dividends Now Qualified Business Income
A final tweak. The new big beautiful Section 199A deduction treats dividends from electing Section 851 qualified business development companies as qualified business income, so in the same way that REIT dividends get treated. Thus, this income produces a Section 199A deduction.
About the Inflation Adjustment
And a postscript: When I asked ChatGPT to review my draft for this post, it suggested I point out one other tweak: The new law resets the base year for inflation adjustments to 2025 so taxpayers don’t lose several years of CPI increases. Which is a good point.