4.__Contractor's remedy.__An owner of a public improvement that retains for more than 30 days any funds in excess of those properly calculated from the punch list or that retains any contract funds more than 30 days beyond final completion is liable to the contractor for interest on overdue amounts at the rate of 1.5% per month and for reasonable attorney's fees for collection of overdue funds.

5.__Secured releases.__Under any contract made for a public improvement, the contractor may withdraw retained funds upon depositing with the Treasurer of State or the public owner negotiable public securities or certificates of deposit greater in value than the amount withdrawn.

6.__Authority of Treasurer of State or owner.__The Treasurer of State or the owner of a public improvement shall pay over to the contractor all net income from the escrowed securities as it is received.__The Treasurer of State or the owner may contract with a suitable financial institution for custodial care and servicing of any securities deposited pursuant to this section.

7.__Deductions.__Any amount deducted by the owner of a public improvement, pursuant to the terms of the contract, from the retained payments due the contractor must be deducted, first from that portion of the retained payments for which no security has been substituted, then from the proceeds of any deposited security. In the latter case, the contractor is entitled to receive interest, coupons or income only from those securities that remain after the deduction has been made.

8.__Assignments.__Any assignment of retained payments made by the contractor of a public improvement must be honored by the party holding the securities as part of the procedure to accomplish the substitution of securities under this section, provided that such an assignment may not be made without prior notification to the contracting agency of the State and the party holding the securities.__Such an assignment does not impair the equitable rights of the contractor's surety in the retained payments or in the securities substituted therefor in the event of the contractor's default in the performance of the contract or in the payment of labor and material bills or other obligations covered by the surety's bond.