What is Tax Credit?
A tax credit reduces your tax bill dollar for dollar. It's the most powerful kind of tax break there is.
How it works
Credits come off your calculated tax directly, not your income. A $2,000 credit erases $2,000 of tax, period — regardless of your bracket. Some are nonrefundable (they can zero out your tax but not go below it) and some are refundable (they can pay you the excess).
A quick example
What people get wrong
When you're choosing between a credit and a deduction of the same size, the credit almost always wins. Deductions save you your bracket rate; credits save you the whole amount.