Deduction bunching calculator

By Tom, CPA · Updated October 27, 2026

TL;DR: Bunching means making two to five years of charitable gifts in one year, often through a donor-advised fund, so you itemize that year and take the standard deduction in the others. The 2026 rules change the math: a 0.5%-of-AGI floor on itemized charitable gifts, and a new $1,000 or $2,000 deduction for non-itemizers. This calculator compares total deductions both ways over the bunching period.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

The standard deduction is big: $32,200 for married couples and $16,100 for single filers in 2026 (Rev. Proc. 2025-32). That's great for simplicity and terrible for charitable givers who sit just below it, because their gifts produce little or no tax benefit. Bunching fixes that by stacking several years of gifts into one, like doing all your laundry on one weekend instead of a sock a day.

The 2026 rules added two twists, so old rules of thumb need rechecking. Full explanation: deduction bunching.

CPA Warning Label: Bunching only helps if the bunched year clears the standard deduction by more than you give up in off years. If you sit far below the standard deduction, bunching can actually cost you the small non-itemizer deduction.

How to use it

• Annual giving: cash you'd normally give each year.
• Other itemized deductions: state and local taxes after the cap ($40,400 for most 2026 filers), mortgage interest and medical expenses above 7.5% of AGI. Assumed the same every year.
• AGI: sets the 0.5% floor and the 60% cash gift limit.
• Tax rate: your marginal federal bracket.
• Years: how many years of giving you'd put into one year.

How it calculates

• Giving every year: each year, itemize if other deductions plus giving above 0.5% of AGI beat the standard deduction. If not, take the standard deduction plus the non-itemizer deduction of up to $1,000 single or $2,000 joint (new for 2026 under the 2025 tax law, per IRS guidance).
• Bunching: one year with all the giving (above the 0.5% floor, up to 60% of AGI for cash), then the larger of the standard deduction or your other itemized deductions in the off years. Gifts in off years come from the donor-advised fund, so there's no non-itemizer deduction then; DAF gifts don't qualify for it anyway.

It ignores the 35% cap for the top bracket, the age-65 additional standard deduction and state taxes.

Illustration

Jo and Lee, married, give $10,000 a year with $23,000 of other itemized deductions and $200,000 of AGI, in the 24% bracket.

• Every year: $23,000 + ($10,000 − $1,000 floor) = $32,000, just under $32,200. So they take the standard deduction plus $2,000: $34,200 a year, $102,600 over three years.
• Bunch three years: $23,000 + ($30,000 − $1,000) = $52,000 in year one, then $32,200 twice: $116,400.

Bunching adds $13,800 of deductions, about $3,312 of federal tax saved. Funding the DAF with appreciated shares instead of cash would also avoid capital gains tax; see the donor-advised fund guide.

But a single filer giving $3,000 a year with $8,000 of other deductions gains nothing: even bunched, $13,600 doesn't reach $16,100, and they lose the $1,000 non-itemizer deduction each year. Bunching costs about $440.

When bunching helps, and when it doesn't

The last row matters: a qualified charitable distribution keeps the gift out of AGI entirely, with no floor and no need to itemize. See the QCD checklist. And if your income will drop soon, for example in retirement, bunching gifts into a high-income working year gives each dollar a bigger deduction.

Making it work

• Fund the DAF by December 31 of the bunching year, ideally with long-term appreciated stock.
• Bunch other deductions too, where you can: pay a property tax bill that has been assessed before year-end, or schedule elective medical procedures.
• Plan the off years: you still give through the DAF, so charities see no gap, but you won't get a deduction for those grants.
• Keep acknowledgments for every gift over $250.
• Rerun the numbers each year as income, SALT and mortgage interest change.

See more calculators and tax-efficient giving, ranked.