The Quiet Tax Hikes Hidden in the 2026 Inflation Adjustments

Every fall the IRS publishes the coming year’s inflation adjustments and the headlines call it a “tax cut.” It usually isn’t. The dollar figures move up, but so do wages, asset prices, and phase-out thresholds — and the math built into the code has been quietly ratcheting effective rates higher for years. Chained CPI, lagged measurement windows, and threshold designs that were never indexed at all combine to push HNW filers into higher brackets and phase-outs faster than the sticker figures suggest.

The 2026 numbers are no exception. Here’s where the mechanics actually bite.

Chained CPI is a permanent tax hike disguised as an adjustment

The TCJA replaced traditional CPI-U with the Chained CPI-U (C-CPI-U) as the index used to adjust most tax parameters under § 1(f)(3)(B). OBBBA left that change in place. The difference between the two indices is small in any given year — usually 20 to 30 basis points — but it compounds. Over a decade, C-CPI-U indexing has lifted the top-bracket threshold, the standard deduction, and the estate exemption by several percentage points less than traditional CPI would have.

The mechanic is deliberate. Chained CPI assumes taxpayers substitute cheaper goods as prices rise, so measured inflation runs lower than a fixed-basket CPI. Applied to tax brackets, that means brackets rise more slowly than the price level households actually experience — especially at the high end, where the substitution assumption breaks down completely. No one substitutes a cheaper school or a cheaper primary residence in the way the CPI basket assumes.

For HNW filers, the compounding effect over a full career is meaningful. A top-bracket threshold indexed to C-CPI-U rather than CPI-U is roughly two to three percentage points lower after ten years than it would otherwise be. Applied to marginal income at the top rate, that’s real money — quietly collected without a single vote on a rate change.

What we’re doing about it: we run multi-year projections against the actual index the IRS uses, not against nominal-dollar assumptions. Anyone modeling long-horizon estate, gift, or retirement drawdown numbers off “the current exemption plus 2% a year” is overstating what the exemption will actually buy in real terms.

The measurement window guarantees the adjustment is stale

The inflation adjustment for a given tax year is calculated using the twelve-month period ending August 31 of the prior year. The 2026 brackets are set against C-CPI-U for September 2024 through August 2025. Wages, rents, and asset prices earned or paid in 2026 are compared to a threshold frozen against price levels from a year and a half earlier.

In periods of rising inflation, that lag pulls filers into higher brackets and phase-outs before the adjustment catches up. In 2024 and 2025, the C-CPI-U cadence measurably lagged actual wage growth for higher earners. HNW compensation — bonuses tied to firm performance, RSU vests marked at market, carried-interest allocations, guaranteed-payment increases — moved up faster than the index. The result is that a filer whose real income was flat could still see effective rate creep just from the timing mismatch.

There is nothing anyone can do about the lag itself. What planners can do is treat the published 2026 numbers as backward-looking data, not forward-looking guidance. Compensation-timing decisions, Roth conversions, and installment-sale elections should all be modeled against the real path of the taxpayer’s own income — not against next year’s brackets multiplied by a flat growth rate.

AMT exemption creep is a real problem again post-OBBBA

The Alternative Minimum Tax exemption under § 55(d) is indexed for inflation, but the phase-out threshold moves at the same rate. For a MFJ filer, the AMT exemption phases out at 25 cents per dollar of AMTI above the phase-out threshold. Above the top of the phase-out band, the full exemption is gone.

OBBBA left AMT largely intact. That matters because AMT was a nearly dormant tax for most of the post-TCJA period — the higher exemption and phase-out thresholds pulled the vast majority of filers out of it. But two forces are pulling filers back in:

• ISO exercises. For founders and early employees at private companies, the ISO bargain element remains an AMT preference item under § 56(b)(3). As private-market valuations have climbed and secondary tenders have accelerated, more taxpayers are recognizing large preference items in a single year.
• State tax deduction limitations. The SALT cap interacts with the AMT preference for state and local taxes. For high-CA-tax filers hit by both the cap and the AMT phase-out, the effective marginal rate on additional income in the AMT zone can exceed the headline 37% federal plus 13.3% California stack.

What we’re doing about it: every HNW client with ISO exposure gets an AMT projection before any exercise decision. The pattern that keeps costing money is exercising in December to hit a calendar-year cash target and then discovering in April that the AMT liability wiped out the intended benefit.

The § 199A phase-in thresholds moved — but not evenly

OBBBA made the 20% qualified business income deduction under § 199A permanent and widened the SSTB phase-in range at the top. That’s a real benefit for SSTB owners near the old top of the phase-in — physicians, attorneys, financial-services owners, consultants — who previously saw the deduction disappear entirely above roughly $483K of taxable income for MFJ.

Two things about the new indexing are worth flagging. First, the bottom of the phase-in range moves at C-CPI-U, which lags where SSTB owner incomes actually are. That pushes more owners into partial-deduction territory each year without a headline change. Second, the wage-and-UBIA limitation above the top of the range is unchanged — the deduction is still capped at the greater of 50% of W-2 wages or 25% of W-2 wages plus 2.5% of UBIA of qualified property. For high-income non-SSTB owners with lean payrolls, the wage limit still binds tighter every year as their QBI grows faster than their payroll indexing.

The practical effect for owners near the phase-in threshold is that the 2026 threshold buys less deduction than the 2025 threshold did in real terms, even though the nominal number is higher. Compensation planning, entity structure, and defined-benefit contribution decisions all need to be run against the actual thresholds and the actual income projection — not against a static rule of thumb.

Estate and gift exemption indexing after OBBBA

OBBBA made the elevated estate and gift tax exemption permanent and continued the C-CPI-U indexing under § 2010(c)(3)(B). That’s a real planning stability improvement — the sunset that would have cut the exemption roughly in half didn’t happen. But permanence at C-CPI-U is not the same as permanence in real terms.

The indexing question matters most for families whose taxable estate is currently below the exemption but growing faster than the index. Real estate at prime California addresses, concentrated equity in a founder’s cap table, closely held business interests marked at recent transaction multiples — all of these can compound at rates well above C-CPI-U. A family that is $5M under the exemption today can be $5M over it in a decade purely from asset appreciation outpacing the index.

What we’re doing about it: we’re rebuilding estate projections against realistic asset-growth assumptions rather than the flat “exemption grows at 2%” default. Where the projection shows the estate crossing the indexed exemption within the client’s remaining planning horizon, we look at gifting strategies, SLATs, GRATs, and other freeze techniques while the current exemption still buys the transfer we want. The exemption is permanent; the real-dollar exemption is not.

The uncomfortable truth about the annual bracket update

Inflation adjustments are treated in the popular press as a taxpayer benefit — the government “giving back” some of the effect of inflation. The mechanics don’t support that framing. For most HNW filers, the combination of C-CPI-U indexing, lagged measurement windows, and phase-out thresholds designed to erode exemption benefits over time means the adjustments quietly raise effective rates every year they’re published. The only way to see it is to run multi-year projections against the actual mechanics rather than against nominal-dollar shortcuts.

Long-horizon estate plans, retirement drawdown models, and equity-compensation exercise decisions all need to be built against the code as it actually indexes — not against a flat growth assumption.

If your multi-year projections are still built off flat inflation assumptions and nobody’s stress-tested them against the actual indexing mechanics, that’s a conversation worth having.

Daniel Litvin is CEO of Laléa & Black and leads the firm’s macro and markets practice for HNW families, closely held businesses, and cross-border filers. Laléa & Black is a Los Angeles CPA firm serving clients across taxation, business management, and investment tax strategy.