Which of the following is a non-refundable tax credit?

The Retirement Savings Contributions Credit is categorized as a non-refundable tax credit because it can only reduce a taxpayer's liability to zero, but it does not allow for a refund if the credit exceeds the amount of taxes owed. This particular credit is designed to encourage saving for retirement by providing a direct benefit to individuals who make contributions to qualified retirement accounts, subject to certain income limits.

In contrast, other credits—such as the Premium Tax Credit, Credit for Excess Social Security and RRTA Tax Withheld, and the Earned Income Tax Credit—can be refundable. Refundable credits may result in a refund exceeding the total tax liability, providing additional financial benefits to the taxpayer. Recognizing the nature of these credits and their respective eligibility criteria and structures is essential in understanding their implications for tax liabilities and potential refunds.