Darien

Can you give me an example?
I’ll try:
$200 K in pre-tax funds
30% tax rate.
$100K donated to charity.
Pre-tax left over income= $100K
After-tax left over income = $100K( 1-0.3) = $70K .
Do you get additional rebate on donated money ( $100 K) , even though you did not pay taxes on it?
How can you get rebate ( i.e. deduction ) if you did not pay taxes?