This is the webpage for the Comptroller of Maryland with information for business taxpayers.It explains that sales at Flea Markets in Maryland are subject to the State's 5% sale tax (like most other sales made in the State).
They offer two types of sales tax licenses, a 30 day temporary permit and and a permanent license.
The permanent license is better becuase with it you don't have to pay sales tax on your purchases for resale.
Check out the Comptroller's page for complete details.
Maryland Sales and Use Tax - Flea Market Sales
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