You will have to enter your SSA1099 on your federal return and then the information will flow to the MD return. The software will follow all of your state's tax laws regarding whether the SS is taxable. And....Social Security is NOT taxable in MD.
Go to Federal> Wages & Income>>Retirement Plans and Social Security (SSA1099 and 1099RRB) to enter your SSA1099.
Some additional information: There are 13 states that tax Social Security—Colorado, Connecticut, Kansas, Minnesota, Missouri, Montana, Nebraska, New Mexico, North Dakota, Rhode Island, Utah, Vermont, and West Virginia. These states offer varying degrees of income exemptions, but four mirror the federal tax schedule: MN, ND,VT, and WV