Section 03.04.01.02(A)(4)(b) of the Maryland Code of Regulations says that the unpaid tax subject to interest and penalty is the lesser of
(i) 90 percent of the tax required to be shown on the return for the current taxable year; or
(ii) 110 percent of the tax paid for the prior taxable year, reduced by any credit allowed under Tax-General Article, § 10-703, Annotated Code of Maryland.
03.04.01.02(A)(4)(b)(ii) is the safe harbors that applies in your case. 110% your 2020 Maryland tax liability is zero, so required quarterly payments would be $0.
I can't find any way to tell 2021 TurboTax in step-by-step mode to indicate that your quarterly payments were equal to 1/4 of 110% of the 2020 Maryland tax liability. I've only been able to do it by marking box B on the Maryland Form 502UP in forms mode of the CD/download version of TurboTax. I don't have access to the online version of TurboTax's Maryland module so I don't know if the online version provides this capability, but I doubt it. Marking box B causes TurboTax to omit Form 502UP from your filing.
