Known questioned cost
(4) Known questioned cost means a questioned cost specifically identified by the auditor. Known questioned costs are a subset of likely questioned costs. (5) Likely questioned cost means the auditor's best estimate of total questioned costs, not just the known questioned costs. Likely questioned costs are developed by extrapolating from audit evidence obtained, for example, by projecting known questioned costs identified in an audit sample to the entire population from which the sample was drawn. In evaluating the effect of questioned costs on the opinion on compliance, the auditor considers the likely questioned costs, not just the known questioned costs. (6) Questioned costs are not improper payments until reviewed and confirmed to be improper payments as defined in OMB Circular A-123 Appendix C.