(a) In the case of a mortgage or a deed of trust in which the lender assumes responsibility to the borrower to pay the property taxes on the mortgaged property by the collection of taxes through an expense account arrangement, the lender shall pay the taxes within 45 days after (1) the first due date, (2) receipt of the tax bill by the lender, or (3) the funds collected by the lender are sufficient to pay the amount of taxes and interest due, whichever occurs last.

(b) If a lender has sufficient funds available to pay the taxes, has received a copy of the tax bill, and fails to pay at the time as provided in this section, the lender shall pay the difference between the amount of taxes, interest, and penalty due if paid at the time as provided and the amount of taxes, interest, and penalty due at the time that the taxes, interest, and penalty are actually paid by the lender.