If no tax is due and you requested a federal extension, you don't need to file any forms or take any action to obtain an automatic six month extension.
If you expect to owe Maryland tax, follow the instructions on Form PV to request an extension of the time to file your 2018 return. Filing this form extends the time to file your return, but doesn't extend the time to pay your taxes. Payment of the expected tax due is required with Form PV by April 15, 2019.
Only submit Form PV if tax is due.
Use the Form PV Extension Worksheet to help calculate your payment.
If you do not expect to owe tax and have not requested a federal extension, you may request a Maryland extension by telefile by calling 410-260-7829 from central Maryland or 1-800-260-3664 from elsewhere.