[saberience]

That’s not how tax deductions work because a tax deduction doesn’t give you the full amount of your donation back it only reduces your taxable income, not your tax bill dollar-for-dollar.

Example:

You earn $100,000.

You donate $10,000 to a qualifying charity.

You can now deduct that $10,000, i.e. you’ll be taxed as if you earned $90,000, not $100,000.

If your marginal tax rate is 30%, you’ll save 30% of $10,000 = $3,000 in taxes. So you’re still out $7,000 in real money.

[yazmeya]

Though if that 100K to 90K move had actually changed your tax bracket, you'd stand to maybe save a bit more.

[ben-schaaf]

It changes nothing. If you get taxes 20% til 90k and 30% above that, then donating 10k still saves you 3k in taxes, you're still out 7k and you're still paying 18k in taxes on the 90k.