CMS provided an update explaining why some EP's who attested have not recieved their incentive check with the 6 - 8 week timeframe.
The maximum incentive check is $18,000 or 75% of the Medicare Allowed amount, whichever is less. When an EP hits $24,000 in Medicare allowable they have reached the maximum incentive amount. If an EP attests, and they have not yet met the $24,000 threshold the check is held until that threshold is reached. This way the EP does not have to apply for the balance and CMS does not have to write 2 or more checks.