The arithmetic looks simple — a fixed cap on one side, a percentage on the other. The part that goes wrong by hand is which rule applies to which path, and in what order.
| Step | Common mistake by hand | What this calculator does |
|---|---|---|
| 0.5% floor scope | Applies the new floor to the non-itemizer deduction too. | Only reduces the itemized path — the non-itemizer above-the-line deduction is never touched by the floor. |
| Non-itemizer cap | Treats the $1,000/$2,000 cap as per-gift rather than per-year. | Caps your TOTAL cash giving for the year at the filing-status figure, not each individual donation. |
| Order of limits | Applies the 0.5% floor to uncapped giving, before the 60%-of-AGI ceiling. | Applies the 60%-of-AGI ceiling first, then subtracts the 0.5% floor from that capped figure. |
| Donor-advised funds | Assumes a DAF contribution qualifies for the non-itemizer deduction. | Flags that only direct cash gifts to public charities qualify — DAF contributions do not. |
| Is anything I enter uploaded anywhere? | N/A | No. The calculator runs entirely in your browser; nothing is sent to a server. |
Applying the new 0.5%-of-AGI floor to the non-itemizer deduction too. The floor only applies if you itemize on Schedule A — the new $1,000/$2,000 above-the-line deduction for non-itemizers is not reduced by it at all.
Treating the $1,000/$2,000 non-itemizer cap as a per-gift limit rather than a total-for-the-year cap. It is the maximum deduction for ALL your cash giving to public charities combined in the year, not per donation.
Forgetting the order the limits apply in. The existing 60%-of-AGI ceiling caps what could ever be deductible first; the new 0.5%-of-AGI floor is then subtracted from that capped figure. Applying the floor to your full, uncapped giving figure overstates how much the ceiling costs you.
Assuming a donor-advised fund contribution qualifies for the non-itemizer deduction. It does not — only direct cash gifts to public charities qualify for the new $1,000/$2,000 above-the-line deduction.
No. Neither this calculator nor a by-hand worksheet built from this page knows your other itemized deductions, whether itemizing beats your standard deduction overall, or the separate top-bracket itemized-deduction limitation. Both apply the same published federal rules to the numbers you enter; verify against IRS guidance or a qualified tax professional before relying on either.