Many US donors will be able to claim back a significant portion of their donation that would otherwise be taxed. The money that can be claimed from a tax deductible donation will enable you to be more generous than you initially thought.
Giving What We Can members can automatically track donations made via Giving What We Can to their pledge without needing to report them separately.
You claim a tax deduction on a charitable contribution by including it as an itemized deduction on your individual income tax return (in Schedule A of Form 1040). To do this you will need a receipt of your contribution, which will be provided by the organisation you have donated to.
You will not be able to claim a tax-deduction on your donation if you use a "standard deduction" instead of itemizing your deductions on your tax return.
More information (including Schedule A and Form 1040) can be found here.
This website will calculate the amount that you can claim back from your donation.