A unit is not liable under § 15-104 of this subtitle for interest: unless within 30 days after the date on the State’s check for the amount on which the interest accrued, the contractor submits an invoice for the interest; if a contract claim has been filed under Subtitle 2 of this title; accruing more than 1 year after the 31st day after the unit receives an invoice; or on an amount that represents unpaid interest.