Charities are classified as "20% limit", "30% limit" and "50% limit" organizations. That means, roughly speaking, you can donate 50% of your income to a 50% charity and take a deduction, but if you donate more, the unused portion of the deduction is carried forward to future tax years. If you donate in the same year to 20%, 30% and 50% charities, the limits get applied in a confusing way. You can read more about it here.
https://www.irs.gov/pub/irs-pdf/p526.pdf
Even though the top category is called "50% charities", the actual limit for cash contributions was temporarily raised to 60% through 2025.
