Contributions to a 529 plan are not deductible on the federal return.
Per the IRS 529 Plans: Questions and Answers webpage:
A. Earnings are not subject to federal tax and generally not subject to state tax when used for the qualified education expenses of the designated beneficiary, such as tuition, fees, books, as well as room and board at an eligible education institution and tuition at elementary or secondary schools. Contributions to a 529 plan, however, are not deductible.
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