Except to the extent a shorter period is prescribed by regulation governing differing site conditions, a contractor shall file a written notice of a claim relating to a procurement contract within 30 days after: for requests for equitable adjustments, the later of: a unit denying a request for equitable adjustment; or one of the parties notifying the other party in writing that the notifying party determined the discussions reached an impasse in attempting to resolve their disagreement regarding the request; and for other claims, the basis for the claim is known or should have been known. Unless extended by the unit, within 90 days after submitting a notice of a contract claim under a procurement contract, a contractor shall submit to the unit a written explanation that states: the amount of the contract claim; the facts on which the contract claim is based; and all relevant data and correspondence that may substantiate the contract claim. On receipt of a timely contract claim from a contractor, a procurement officer: shall review the substance of the contract claim; may request additional information or substantiation through an appropriate procedure; may conduct negotiations with the contractor initiating the contract claim; and shall comply with any applicable regulations. Unless clearly inappropriate, the procurement officer shall seek the advice of the Office of the Attorney General on any legal issues. Subject to subsection (c) of this section and consistent with the State budget and other applicable laws, the procurement officer shall: resolve the contract claim by agreement of the parties; wholly or partly deny the contract claim; or wholly or partly grant the relief sought by the claimant. Except as provided under paragraph (3) of this subsection, for a contract other than a construction contract, the reviewing authority shall approve, disapprove, or modify the decision of the procurement officer within 180 days after receiving the contract claim or a longer period to which the parties agree. The action of the reviewing authority under this subsection shall be the final action of the unit. The reviewing authority may remand the proceeding with instructions to the procurement officer. On remand, in accordance with the reviewing authority’s instructions, the procurement officer shall proceed in accordance with subsection (c) of this section. Subject to paragraph (2) of this subsection, for a construction contract, the head of the unit engaged in procurement or the head’s designee shall review the contract claim and the decision of the procurement officer. If the unit is part of a principal department or other equivalent unit, the Secretary of the principal department or the equivalent official or the Secretary’s designee or the official’s designee shall review the contract claim and the decision of the procurement officer, unless review has been delegated by regulation to the head of the unit. The person who reviews a contract claim under subsection (f) of this section shall: investigate the contract claim; and give the contractor written notice of a resolution of the contract claim: within 90 days after receiving the contract claim or a longer period to which the parties agree, if the amount of the contract claim is not more than the amount under which the accelerated procedure may be selected before the Appeals Board; or for any other contract claim, within 180 days after receiving the contract claim or a longer period to which the parties agree. Recovery under a contract claim is not allowed for any expense incurred: more than 60 days before the required submission of a notice of a claim under subsection (a) of this section; or unless the time for submission of a claim is extended under subsection (b) of this section, more than 150 days before the required submission of the claim. If the unit determines that it is responsible for a portion but not all of the amount claimed by the contractor, subject to the terms of the contract, the unit shall pay the undisputed amount. Payment of the undisputed amount: is not an admission of the liability of the unit on the claims; and does not preclude recovery of the amount paid if it subsequently is determined that the determination of the unit was not correct. A decision not to pay a contract claim is a final action for the purpose of appeal to the Appeals Board. Prior to authorizing payment on a claim, the procurement officer shall require the contractor to supplement the claim with a certification by a senior officer or general partner of the contractor or the subcontractor, as applicable, that, to the best of that person’s knowledge and belief: the claim is made in good faith; all supporting data is accurate and complete; and the amount requested accurately reflects the contract claim for which the person believes the procurement agency is liable. At the time of final payment, the unit shall: release the retainage due to the contractor; and pay any interest that: has accrued on the retainage from the time of payment of the semifinal estimate; and is due and payable to the contractor.