Facts registry
What is the 2026 floor on itemized charitable deductions, share of contribution base (§170(b)(1)(I))?
0.5%
The Floor on itemized charitable deductions, share of contribution base (§170(b)(1)(I)) for TY2026 onward is 0.5%. Source: Public Law 119-21 (One Big Beautiful Bill Act) (§70425). Checked against that source on 2026-10-11.
Where it comes from
- Value
- 0.5%
- Applies to
- TY2026 onward
- Jurisdiction
- United States, federal
- Primary source
- Public Law 119-21 (One Big Beautiful Bill Act) (§70425)
- Last checked
- October 11, 2026
- Registry id
- irs.charitable.agi-floor.2026
§70425(a): "Any charitable contribution otherwise allowable (without regard to this subparagraph) as a deduction under this section shall be allowed only to the extent that the aggregate of such contributions exceeds 0.5 percent of the taxpayer's contribution base for the taxable year." Contribution base is AGI (§170(b)(1)(H)). Applies after the percentage limits ("otherwise allowable").
Calculations that use it
When one of these runs, the response returns this constant alongside the result, with its source — so a number in an answer traces back to the notice that set it.
Get it programmatically
The whole registry as JSON — every constant with its value, period, primary source, and check date. No key required.
curl https://worthune.com/api/v1/factsQuestions
Common questions
- What is the 2026 floor on itemized charitable deductions, share of contribution base (§170(b)(1)(I))?
- The Floor on itemized charitable deductions, share of contribution base (§170(b)(1)(I)) for TY2026 onward is 0.5%. Source: Public Law 119-21 (One Big Beautiful Bill Act) (§70425). Checked against that source on 2026-10-11.
- Where does this number come from?
- Public Law 119-21 (One Big Beautiful Bill Act) (§70425). We record the primary source for every constant our models use, along with the date a person last checked the value against it — in this case 2026-10-11. A figure without a source and a date cannot be told apart from a stale one.
- Which calculations use this figure?
- One Worthune model uses it: charitable-bunching. When one of them runs, the response returns this constant alongside the result, with its source, so the number in an answer can be traced back to the notice that set it.
- How do I get this figure programmatically?
- GET https://worthune.com/api/v1/facts returns the whole registry as JSON — every constant with its value, period, primary source, and check date. No key is required.
We maintain this registry against its primary sources on a best-efforts basis and version every change publicly. It is reference information, not tax or financial advice — verify against the primary source before relying on a figure. Spotted something wrong or out of date? Tell us at support@worthune.com.