Section 63.5541 - When must I conduct subsequent performance tests?(a) For each affected source utilizing a non-recovery control device to comply with § 63.5515 that commenced construction or reconstruction before September 9, 2019, a periodic performance test must be performed by July 2, 2023, and subsequent tests no later than 60 months thereafter.(b) For each affected source utilizing a non-recovery control device to comply with § 63.5515 that commences construction or reconstruction after September 9, 2019, a periodic performance test must be performed no later than 60 months after the initial performance test required by § 63.5535 , and subsequent tests no later than 60 months thereafter.85 FR 39995, July 2, 2020