Can a tax deduction ever be worth more than a tax credit of the same size?

Rarely, but it can happen at the margins. Normally a $1,000 credit beats a $1,000 deduction because the credit is worth the full $1,000 while the deduction is only worth your bracket times $1,000. The exception involves knock-on effects: an above-the-line deduction lowers your adjusted gross income (AGI), and a lower AGI can unlock other benefits like larger medical or charitable thresholds, bigger IRA deductibility, or eligibility for income-tested credits. A credit does not change your AGI. So a deduction that also rescues a phased-out benefit can occasionally deliver more total value. For most filers, though, a credit still wins dollar for dollar, and the IRS treats above-the-line deductions as especially useful because they reduce AGI directly.