If you are the account owner or a contributor, you can subtract up to $2,500 per beneficiary from your Maryland state income for contributions in that calendar year. Contributions in excess of $2,500 per beneficiary can be subtracted for up to the next 10 years. Maryland 529
To report your 529 contribution:
Open your state return and continue to the screen Here's the income that Maryland handles differently.
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Click start next to Maryland college savings plan contributions