in terms of Federal taxes a deduction means roughly 1/3 back
You cannot deduct 529 plan contributions on a Federal return.
https://www.irs.gov/uac/529-plans-questions-and-answers
The MD state deduction is worth whatever your marginal state tax rate is.
http://taxes.marylandtaxes.com/Individual_Taxes/Individual_Tax_Types/Income_Tax/Tax_Information/Tax_...
