2026 Itemized Deduction Planning: How High Earners Can Protect the Full Tax Benefit

High-income taxpayers can no longer assume that every dollar reported on Schedule A offsets income at the 37% federal rate. Beginning in 2026, Section 68 applies a new overall reduction after the tax law has already limited charitable contributions, state and local taxes, medical expenses, investment interest, and other itemized deductions.

The calculation is compact, but the planning is not. A large bonus, business sale, Roth conversion, option exercise, concentrated-stock gain, or partnership allocation can move a household into the limitation. The result affects year-end cash flow, the timing of gifts and state payments, and the estimated tax due on September 15, 2026 and January 15, 2027.

How Section 68 Changes Itemized Deductions in 2026

The new Section 68 rule is not the old Pease limitation. It does not reduce deductions by 3% of AGI above a threshold, and it does not use the former 80% maximum reduction. Instead, it reduces the itemized deduction itself by 2/37, approximately 5.4%, of a defined lesser amount.

The two comparison amounts are:

1. the taxpayer's otherwise allowable itemized deductions after other deduction-specific limits; and
2. the amount by which taxable income, computed before Section 68 and increased by those itemized deductions, exceeds the threshold where the 37% bracket begins.

If the second amount is lower, only that portion is exposed to the haircut. If total itemized deductions are lower, the full deduction base receives the 2/37 reduction. Public Law 119-21 also directs that Section 199A qualified business income deductions be computed without regard to Section 68, so the new limitation does not directly shrink QBI.

Who Crosses the 2026 Thresholds

For 2026, IRS Publication 505 identifies the Section 68 testing thresholds as $768,700 for married taxpayers filing jointly and qualifying surviving spouses, $640,600 for single taxpayers and heads of household, and $384,350 for married taxpayers filing separately.

These are not simple AGI phaseouts. Taxpayers should use the statutory formula and the IRS worksheet rather than comparing gross income to a headline number. A taxpayer below the Section 68 threshold may still face other limits, including the 0.5% charitable floor, the medical-expense AGI floor, investment-interest rules, and the 2026 SALT cap.

For 2026, Publication 505 states that the individual SALT deduction limit is $40,400, or $20,200 for married filing separately. The cap begins to phase down when modified AGI exceeds $505,000, or $252,500 for married filing separately, but generally cannot fall below $10,000 or $5,000, respectively. Section 68 is applied only after that SALT calculation.

The Calculation Order Matters

A high-earner projection should follow the same order the law follows:

1. Build each deduction. Determine deductible mortgage interest, investment interest, taxes, medical expenses, casualty losses, and charitable contributions under their own rules.
2. Apply specific limits. Reduce charitable contributions by the new 0.5% AGI floor, apply percentage limits and carryforward rules, and apply the SALT cap and phase-down.
3. Total Schedule A deductions. Compare the allowable total with the standard deduction, which is $32,200 for married filing jointly, $16,100 for single or married filing separately, and $24,150 for head of household in 2026.
4. Apply Section 68. Compute 2/37 of the lesser statutory amount and subtract it from total itemized deductions.
5. Recompute tax and payments. Run ordinary income, qualified dividends, capital gains, NIIT, AMT, withholding, and estimated-tax safe harbors together.

This ordering prevents a common model error: applying a flat 5.4% haircut to gross payments before determining whether those payments are deductible at all.

Planning Moves Before Year-End

• Update the full-year projection now. Include bonuses, K-1 estimates, equity compensation, Roth conversions, capital gains, business-sale proceeds, and trust distributions. Section 68 planning cannot be done from last year's AGI alone.
• Concentrate charitable gifts deliberately. Bunching multiple years of gifts into one year may help donations clear the 0.5% floor. Donor-advised funds can support that timing, while gifts of appreciated securities may also avoid embedded capital gain. The deduction and gain-avoidance benefits should be modeled separately.
• Coordinate SALT and PTET elections. IRS Notice 2020-75 generally permits qualifying state income taxes imposed on and paid by a partnership or S corporation to be deducted at the entity level. State eligibility, election windows, owner credits, addbacks, and cash deadlines vary, so confirm the applicable state rules before moving a payment.
• Model extraordinary income across tax years. A closing date, installment sale, option exercise, or Roth conversion can determine how much of the deduction base is exposed to Section 68. Economic and legal terms should drive the transaction, but tax timing belongs in the decision model.
• Do not accelerate deductions mechanically. Paying an expense earlier is useful only if it is deductible, clears any floor, produces a better marginal benefit, and does not create a liquidity or AMT problem.

Estimated Tax and Documentation Checkpoints

IRS Publication 505 includes a 2026 Estimated Charitable Contribution Deduction Worksheet and an Overall Limitation on Itemized Deductions Worksheet. Those worksheets provide a practical bridge from the new law to a current-year tax projection. As of August 1, 2026, the remaining calendar-year estimated-tax installments are due September 15, 2026 and January 15, 2027, subject to the usual weekend, holiday, filing, and taxpayer-specific rules.

High earners should also reconcile year-to-date withholding. Withholding changes late in the year may affect penalty calculations differently than late estimated payments, but payroll timing and safe-harbor rules require taxpayer-specific review.

Maintain a Schedule A workpaper with tax payment confirmations, mortgage-interest records, investment-interest support, charitable acknowledgments, donor-advised fund statements, noncash basis records, qualified appraisals when required, and Form 8283 support. Documentation does not increase the statutory deduction, but it protects the amount the model assumes.

Common Mistakes

• Using AGI as the Section 68 threshold test. The statute uses a defined taxable-income calculation, and Publication 505 provides the worksheet mechanics.
• Applying Section 68 before other limits. The charitable floor, percentage caps, SALT limit, and other item-specific rules come first.
• Assuming every deduction is worth exactly 35%. The 35-cent result is the ordinary-income case when the full deduction base is exposed; capital gain rates, AMT, and partial exposure can change the marginal result.
• Ignoring the new charitable floor. A recurring gift program may generate less deductible value in 2026 even before Section 68 applies.
• Treating PTET as automatic. State elections, deadlines, entity types, owner eligibility, and credit mechanics differ.
• Leaving estimated taxes unchanged. A deduction haircut combined with a bonus, gain, or K-1 increase can create an avoidable underpayment.
• Projecting only federal tax. State conformity and residency can change whether bunching, PTET, or transaction timing creates a net benefit.

The Bottom Line

Section 68 turns itemized deductions into a marginal-rate planning issue for households near or above the 37% bracket. The right response is a coordinated 2026 projection: apply the charitable and SALT limits first, calculate the Section 68 haircut, model ordinary income and investment income together, and update withholding or estimated payments before the remaining deadlines. A deduction strategy is only complete when its tax value, cash timing, documentation, and state result are visible in the same model.