Maryland Tax - General Section 13-602

      (a)      Except as provided in subsections (b) and (c) of this section, a tax collector shall assess interest on unpaid tax from the due date to the date on which the tax is paid if a person who is required to estimate and pay financial institution franchise tax, public service company franchise tax, or income tax under § 8-210(b), § 8-405(b), or § 10-902 of this article:

            (1)      fails to pay an installment when due; or

            (2)      estimates a tax that is:

                  (i)      less than 90% of the tax required to be shown on the return for the current taxable year; and

                  (ii)      less than 110% of the tax paid for the prior taxable year, reduced by the credit allowed under § 10-703 of this article.

      (b)      Interest may not be assessed on the underestimation of individual income tax if:

            (1)      at least 90% of the individual's taxable income is also taxable by another state; and

            (2)      the underestimation is of the county income tax only.

      (c)      A tax collector may not assess interest on unpaid individual income tax under subsection (a) of this section if the amount of unpaid income tax is less than one-half the amount specified in § 6654(e)(1) of the Internal Revenue Code.