Contractor past performance evaluations are important factors in source selection decisions under Parts 8 and 15 of the Federal Acquisition Regulation (“FAR”), and they can easily make or break a contractor’s federal customer base. Especially vulnerable are contractors competing in Lowest Price Technically Acceptable (“LPTA”) procurements, where a bad past performance rating can make contractors ineligible due to an “unacceptable” technical rating even though they may offer the lowest price. The submission by Government contracting officials of a contractor’s performance evaluation to the Contractor Performance Assessment Reporting System (“CPARS”) is required in most instances; however, the contractor’s remedies for correcting poor performance evaluations due to mistakes and material omissions by the evaluator are limited in both time and scope. And as the DoD’s Inspector General (“IG”) has repeatedly pointed out, most recently in its May 9, 2017 report, Summary of Audits on Assessing Contractor Performance (noting a large percentage of DoD performance assessment reports are late and not prepared correctly and accurately), mistakes often happen. Contractors looking to sustain their business in the federal marketplace need to be properly armed with the weapons available to challenge poor performance evaluations when the agency gets it wrong.