Net Cost of Charitable Giving at 37% Tax Bracket

A $100,000 cash gift to charity used to cut a top-bracket donor’s tax bill by $37,000. As of the 2026 tax year, that same gift returns at most $35,000 — and only on the portion that clears a new floor equal to 0.5% of adjusted gross income. The One Big Beautiful Bill Act, signed July 4, 2025, quietly raised the net cost of giving for the highest earners while leaving the sticker price of generosity untouched.

The gap looks small. Two cents on the dollar. At scale and after the floor, it reshapes the arithmetic that has governed high-income charitable planning for the better part of a decade. This analysis works the numbers at the 37% marginal bracket using 2026 rules, and calculates what actually reaches charity per net dollar committed.

The 2026 numbers at a glance

Three federal changes now sit between a top-bracket donor and the deduction they would have claimed in 2024. The deduction value cap. The AGI floor. And the unchanged — but newly more valuable by contrast — treatment of appreciated assets.

Sources: IRS Publication 526 (2025); Tax Foundation analysis of OBBBA charitable provisions (Feb 2026); Fidelity Charitable, “One Big Beautiful Bill: Impact on Charitable Giving” (2026). Net cost assumes the gift clears the 0.5% AGI floor and the deduction is valued at the 35% cap.

Working the marginal tax math

Net cost of a donation equals the gross gift minus the federal tax value of the deduction minus any state tax value. Before 2026, a 37% donor subtracted 37 cents of federal benefit from every deductible dollar. The out-of-pocket cost of a $100,000 cash gift was $63,000.

Two things changed that. The OBBBA caps the value of itemized deductions at 35% for taxpayers whose income lands in the top bracket, so each deductible dollar now returns 35 cents federally rather than 37. The new rule limits the value of itemized deductions to 35 cents per dollar, rather than the 37 cents that’s normal for the top bracket. Separately, the first 0.5% of AGI in contributions is not deductible at all.

Run a full example. A donor with $2 million AGI gives $100,000 in cash to a public charity. The floor is 0.5% of $2 million, or $10,000 — nondeductible. The remaining $90,000 is deductible at the 35% cap, worth $31,500 in federal tax reduction. Net cost of the $100,000 gift: $68,500. The same gift in 2024 cost $63,000. The floor did most of the damage here; at higher AGI it bites harder in absolute dollars, though it shrinks as a share of very large gifts.

Strip the floor out to isolate the cap’s effect — appropriate for a donor whose giving vastly exceeds 0.5% of AGI, where the floor is a rounding error. On the marginal dollar above the floor, a $100,000 gift is valued at 35%, so the deduction is worth $35,000 and net cost is $65,000. That $65,000 net cost is the cleanest 2026 benchmark for the top bracket, and the one this analysis uses for the efficiency calculation below.

The Finluxy Giving Efficiency Rate

The Finluxy Giving Efficiency Rate measures net dollars reaching charitable purpose divided by gross dollars the donor actually spends out of pocket, times 100. It answers a question the deduction percentage alone obscures: for every net dollar of personal cost, how much charitable impact does the donor generate? Higher is more efficient.

Direct cash giving at the 2026 top bracket illustrates the mechanic. A $100,000 gift clears the floor, reaches the charity in full, and costs the donor $65,000 net after the 35%-capped deduction. Rate: 100,000 ÷ 65,000 × 100 = 153.8%. The donor moves $1.54 of charitable impact for every net dollar spent. Under 2024’s 37% math, the identical gift scored 158.7%. The cap alone knocked roughly five points off giving efficiency for the wealthiest donors.

Finluxy calculations under 2026 OBBBA rules. Deduction valued at the 35% cap; floor excluded to isolate vehicle-level efficiency. Appreciated stock assumes $80,000 embedded long-term gain taxed at 23.8% if sold ($19,040 avoided), so net cost = $100,000 − $35,000 deduction − $19,040 avoided tax = $45,960. *Private foundation figure reflects the 1.39% excise tax on net investment income (IRC §4940) as an ongoing drag on assets before granting; setup and administration costs are additional and modeled separately below.

Why appreciated stock widens the gap in 2026

The deduction cap hit cash and appreciated assets equally on the deduction side — both now cap at 35%. But appreciated securities carry a second lever the cap never touched: the capital gains tax the donor never pays. The cap does not apply to the elimination of capital gains on appreciated assets transferred to a charity.

Consider $100,000 of stock bought years ago for $20,000. Sold, the $80,000 long-term gain triggers 23.8% in federal tax — $19,040 — at the top rate with the net investment income surtax. Donate the shares instead and that liability vanishes while the donor still deducts the full $100,000 fair market value. You deduct the current value without ever paying capital gains tax on the appreciation. Net cost drops to $45,960, and the Finluxy Giving Efficiency Rate climbs to 217.6% — versus 153.8% for cash.

The 2026 changes make this spread more decisive, not less. As the deduction cap erodes the value of cash giving, the capital-gains-avoidance advantage of donating appreciated securities becomes a larger share of the total tax benefit. Analysts across the sector expect the cap to push the wealthiest donors toward non-cash vehicles precisely for this reason. One caveat from Publication 526: appreciated property deducted at fair market value is capped at 30% of AGI, versus 60% for cash, with a five-year carryforward for the excess.

DAFs, foundations, and the overhead question

A donor-advised fund changes none of the deduction math. Fund a DAF with $100,000 of appreciated stock and the deduction, the capital gains avoidance, and the net cost are identical to a direct gift of those shares — $45,960 net, 217.6% efficiency at the moment of funding. What the DAF adds is timing control. The donor takes the full deduction now and recommends grants later, which matters enormously under the 0.5% floor.

The floor is an annual hurdle. Give $8,000 a year against a $400,000 AGI and the first $2,000 dies at the floor every single year. Bunch four years of giving into one $32,000 DAF contribution and the floor claims $2,000 once instead of $8,000 across four years. Using a Donor-Advised Fund facilitates this strategy, allowing you to take the immediate, large deduction while distributing grants to charities over time. That is the mechanical case for a DAF in 2026, independent of any deduction-rate argument. The tradeoff is sponsor fees, typically an annual asset-based charge that trims what eventually grants out; the full cost structure of a DAF deserves its own scrutiny.

At the sector level, the pass-through story holds up. The Annual DAF Report for fiscal year 2024 — the dataset the National Philanthropic Trust originated and the DAF Research Collaborative now produces — recorded total assets in DAFs of $326.45 billion, contributions of $89.64 billion, and grantmaking of $64.89 billion, with an overall payout rate of 25.3%, up 1.3 percentage points from the prior year. That payout rate roughly triples the 8% posted by private foundations in the same dataset, which bears on the efficiency comparison below.

The private foundation carries costs a DAF does not. Setup runs into legal and IRS filing fees, annual administration is ongoing, and the foundation owes an excise tax of 1.39% of net investment income under IRC Section 4940, with no reduced rate available. That 1.39% is a permanent annual drag on the investment pool before a single grant goes out. For donors weighing control against cost, the structural tradeoffs between a DAF and a foundation turn on how much governance the donor genuinely needs, and the full overhead of a private foundation rarely pencils out below a mid-seven-figure commitment. Cash to a foundation also deducts at only 30% of AGI, not 60%, tightening the annual ceiling further.

The overlooked insight: the floor, not the cap, is the real 2026 tax

Most 2026 coverage leads with the 35% cap — the headline 200-basis-point haircut on the wealthiest donors’ deductions. The dollar figures say the floor matters more for the target reader. At $2 million AGI, the 0.5% floor removes $10,000 of deduction before any cap applies. Valued at 35%, that lost deduction costs the donor $3,500 in tax — every year giving stays below the bunching threshold.

The cap, by contrast, costs two cents per deductible dollar. On a $100,000 gift above the floor, that’s $2,000. The floor’s $3,500 annual bite exceeds the cap’s $2,000 on a six-figure gift — and unlike the cap, the floor punishes consistent annual givers specifically, the donors least likely to bunch. The donor segment most affected is the band that produces the majority of mid-level fundraising revenue — the loyal annual giving program donors, for whom the floor is now consuming a material slice of their deduction. The efficient response is structural: concentrate giving into fewer, larger years and clear the floor once. A donor who ignores the cap and fixes their giving cadence captures most of the available savings.

QCDs: the one route the cap and floor both miss

Donors past 70½ have a lever that sidesteps both new limits entirely. A qualified charitable distribution sends money directly from an IRA to charity, and because it never enters AGI, it faces neither the deduction cap nor the 0.5% floor. QCDs are above-the-line deductions that directly reduce a taxpayer’s AGI, potentially reducing the amount owed for the 3.8% surtax on net investment income or income-driven Medicare premiums. For 2026 the ceiling is $111,000 per IRA owner. For an older top-bracket donor already taking required minimum distributions, the QCD’s AGI-exclusion math often beats an itemized cash gift outright in 2026.

What this means for a $150k+ household

The 35% cap only binds once income clears the top-bracket threshold — roughly $625,000 in taxable income for a single filer, $750,000 for joint filers. A household at $150,000 to $600,000 sits below that ceiling and still deducts at its full marginal rate, whether that’s 24%, 32%, or 35%. For most of the Finluxy readership, the cap is a non-event; the 0.5% floor is not.

The floor applies to every itemizing household regardless of bracket. At $150,000 AGI it removes the first $750 of giving. At $400,000, the first $2,000. A household giving a few thousand dollars a year may find much of it no longer deductible — which is the argument for bunching multiple years into a single DAF contribution and taking the standard deduction in the off years. The threshold decision for this income band is not which exotic vehicle to use; it is whether annual giving clears the floor at all, and if not, whether to consolidate. Households with appreciated stock and a giving budget above roughly $10,000 a year get the cleanest win: fund a DAF with securities, avoid the 23.8% capital gains hit, deduct full fair market value at the household’s own marginal rate, and grant on the household’s own schedule. The two-cent cap that dominates the headlines was written for a wealthier taxpayer than most of this readership — but the floor was written for everyone, and it rewards households that plan their giving cadence over those that give the same modest amount every December.