The Government Accountability Office (GAO) requires that important contractual agreements be reduced to writing if the parties wish to make the agreement legally enforceable. The GAO's procedures for filing an agency protest include steps such as submitting a written protest, providing evidence, and appealing to the GAO or another level of government. A contractor is entitled to receive certain additional costs of performance plus a reasonable profit on those costs if their interpretation of contract requirements differs from the government's. Additionally, protests can be filed with the GAO, which lacks the power to enforce its decisions, and suspected violations of the Procurement Integrity Act must be reported to the federal agency responsible for the procurement within 3 days.