But the $4000 not a tax credit. It’s a tax deduction. With a tax credit, you deduct the amount directly from the taxes you owe. But with a tax deduction, you deduct the amount from your taxable income.
Big difference.
Disclaimer: That’s my understanding. If I’m wrong here, I hope someone will offer a correction.
Not only that, but the deduction phases out/away with modestly higher senior incomes.