A public construction contract shall provide for partial payment based upon work completed. The contract shall provide that up to five percent of all partial payments made shall be withheld as retainage. Upon 50% completion of project this can be reduced to 2.5%.

• 61 O.S. § 113.1
• 61 O.S. § 113.2

Note:  Withdrawing of any retainage is subject to Oklahoma Statutes mandates. A recommended best practice is to review this subject with the district attorney.
61 O.S. § 123

All statements or invoices submitted to the awarding public agency for work performed shall contain a certification by the supervising architect, engineer, or other supervisory officials if no supervisory architect or engineer is employed for the project, that works for which payment is claimed has been performed and that such work conforms to the plans and specifications for the project. No such statement or invoice shall be paid by the awarding public agency without such certification.

If project progressive payments are based on the public agency’s estimated quantities of materials provided and work performed, certifications are not required. Final estimates shall contain a sworn certification signed by the contractor that the work performed, and the material provided conform to the requirements of the contract, plans, specifications, and special provisions.

All awarding public agencies shall make provisions for the inspection of projects prior to acceptance by the agency and shall approve all claims for payment only after proper inspections have been made as provided in the plans and specifications of the project.
61 O.S. § 124