Which form does Thomas use to report his Retirement Savings Contributions Credit?

Thomas reports his Retirement Savings Contributions Credit using Form 8880 because this form is specifically designed for taxpayers who are eligible to claim a credit for contributions made to qualified retirement accounts, including IRAs and employer-sponsored retirement plans. Form 8880 calculates the amount of the credit based on the taxpayer's adjusted gross income and the contributions made during the taxable year.

The other forms mentioned serve different purposes: Form 1040 is the standard individual income tax return form, Form 2441 deals with child and dependent care expenses, and Form 1095-A is used for reporting health insurance coverage obtained through the Health Insurance Marketplace. Therefore, Form 8880 is the appropriate choice for Thomas to report his retirement savings contributions credit.