The Small Nonprofit Retirement Security Act of 2024 extends two existing tax credits to tax-exempt nonprofit organizations to encourage them to establish retirement plans for their employees. Currently, small employers can claim credits for startup costs when creating pension plans and for implementing automatic enrollment in retirement savings accounts, but nonprofits cannot access these incentives because they don't pay income taxes. This bill allows eligible nonprofits to claim these credits as reductions in their payroll taxes, with the credit amount limited to the payroll taxes they actually owe in a given year. The legislation applies to taxable years beginning after December 31, 2024, and includes provisions to transfer funds to Social Security trust accounts to offset any lost payroll tax revenue from the new credits.