How does CMS determine a diagnosis code's highest level of specificity for a specific beneficiary when generating edit 255 ‘Diagnosis Code’?

To pass Encounter Data Front End System (EDFES) edits, diagnoses codes must be valid codes for the respective date of service and should be coded to the highest level of specificity, meaning to the maximum number of digits available for the codes, in the valid code set. The edits used are similar to those used in Original Medicare, so you may refer to the CMS Medical Learning Network (MLN) Publications Medicare Billing: 837P and Form CMS-1500 (October 2016) and Medicare Billing: 837I and CMS Form 1450 (April 2016), which provide references to the relevant guidance in the “Medicare Claims Processing Manual” for guidance on coding specificity requirements.