Not all of the tax law changes in the One Big Beautiful Bill Act (OBBBA) enacted July 4, 2025 favor high-income taxpayers.

For example, effective for tax years beginning after 2025, under Section 70425 of the Act, the charitable contributions tax deduction for individuals is reduced by 0.5% of the taxpayer’s contribution base for the taxable year.

The contribution base is the taxpayer’s adjusted gross income, computed without regard to any net operating loss carryback to the taxable year.

For most taxpayers, this reduction might not seem significant. For example, if John has adjusted gross income of $1,000,000, the reduction would be $5,000.

Taxpayers with much higher income are hit harder. For example, if Jane has adjusted gross income of $20 million, the reduction would be $100,000. Jane would be in the 37% marginal federal income tax bracket plus 3.8% for the net investment income tax, or 40.8%, so this tax law change could increase Jane’s federal income tax liability by $40,800 for 2026 compared to 2025. If Jane makes $100,000 of charitable contributions each year, she should consider accelerating the contributions she would normally make during 2026 to 2025.

Charitable contributions disallowed because of the 0.5% of contribution base reduction are added to the charitable contributions carryover amount that might be deductible during the 5 subsequent tax years. They are only added to the charitable contributions carryover if the deduction ceiling amount is exceeded, such as 60% of the contribution base for cash contributions to qualifying charities. Otherwise, the deduction for the disallowed charitable contributions are lost. In the example above, if Jane made $100,000 of charitable contributions for 2026, the 60% limitation would be $12 million, so the tax deduction for $100,000 would not be added to the charitable contributions carryover and would be lost.

Another OBBBA change effective after 2025 reduces the tax benefit of itemized deductions by 2/37 (about 5.4%) of the lesser of (1) itemized deductions before the “haircut”, or (2) the taxable income of the the taxpayer, before itemized deductions, that exceeds the threshold for the 37% tax bracket. Note this “haircut” applies to itemized deductions after the 0.5% reduction of charitable contributions.

For example, Jane has taxable income for 2026, before itemized deductions, of $20 million, and itemized deductions before the “haircut” of $1,000,000. The 2026 threshold for the 37% tax bracket for a single person is $640,600. The taxable income, before itemized deductions, exceeding the threshold is $20 million – $640,600 = $19,359,400. The “haircut” would be $1,000,000 X 2/37 = $54,054.

Note that taxpayers age 70 1/2 or older may make qualified charitable distributions (QCDs) from a traditional IRA of up to $108,000 for 2025 and $111,000 for 2026. QCDs aren’t taxable and aren’t subject to the contribution base limits that apply for other charitable contributions. QCDs also “count” for satisfying required minimum distribution (RMD) requirements for traditional IRAs that currently apply for taxpayers who reached age 73 during 2025 or the ages when RMDs applied for earlier years.

Taxpayers who haven’t decided where to donate their charitable contributions yet can “park” the funds in a donor advised fund, community foundation or a private foundation. Lower maximum deduction thresholds might apply.

The 0.5% reduction of the charitable contributions deduction and the 2/37 “haircut” of itemized deductions are only two of the significant changes in OBBBA that are making tax planning more complicated, with many different effective dates and thresholds. Taxpayers should consult with tax advisors who work with tax planning software that incorporates these changes and understand the rules for charitable planning.