(a) In cases where a mortgage has been recorded without payment of the appropriate taxes described in Part 642 of this Title (including mortgages for indefinite amounts which have been recorded without the payment of the applicable taxes as described in Part 642 of this Title, where the commissioner has permitted the recording officer to accept for filing a sworn statement of the maximum amount secured or which under any contingency may be secured by the mortgage as if such statement was filed as of the date of the recording of the mortgage) and to the extent the mortgage covers real property located in a county outside the City of New York, interest penalty is imposed at the rate of one-half of one per centum for each month or fraction of a month for the period that the taxes remain unpaid, computed upon the unpaid balance of taxes due.

(b) In lieu of the interest penalty described in subdivision (a) of this section, in cases where it could not be determined from the face of an instrument that a tax was due, or where an advance has been made on a trust mortgage without payment of the tax, interest penalty is imposed at the rate of one per centum for each month or fraction of a month for the period that the taxes remain unpaid, computed upon the unpaid balance of taxes due.

(c) In cases where a mortgage of real property subject to the taxes described in Part 642 of this Title has been recorded in good faith, and the recording officer has held such mortgage nontaxable or taxable at one amount, and it is later determined by the commissioner that it was taxable at a greater amount, the commissioner may cancel the interest penalties in excess of one- half of one per centum per month.