For each nonpayable functional G-code, one of the modifiers listed below must be used to report the severity/complexity for that functional limitation:
CH 0 percent impaired, limited or restricted
CI At least 1 percent but less than 20 percent impaired, limited or restricted
CJ At least 20 percent but less than 40 percent impaired, limited or restricted
CK At least 40 percent but less than 60 percent impaired, limited or restricted
CL At least 60 percent but less than 80 percent impaired, limited or restricted
CM At least 80 percent but less than 100 percent impaired, limited or restricted
CN 100 percent impaired, limited or restricted
The severity modifiers reflect the beneficiary’s percentage of functional impairment as determined by the therapist, physician, or NPP furnishing the therapy services.
Severity modifiers are required to be reported with each functional G-code
Guidelines for Selecting the Severity Modifier
Use the severity modifier that reflects the score from a functional assessment tool or other performance measurement instrument, as appropriate.
In cases where the therapist uses multiple measurement tools during the evaluative process to inform clinical decision making, clinical judgment is used to combine these results to determine a functional limitation percentage.
Therapists can use their clinical judgment in the assignment of the appropriate modifier. Therapists will need to document in the medical record how they made the modifier selection so that the same process can be followed at succeeding assessment intervals.
Use the CH modifier to reflect a zero percent impairment when the therapy services being furnished are not intended to treat a functional limitation.
In some cases for beneficiaries where improvement is expected to be limited, the same severity modifier may be used in reporting the current and goal status.
In cases where the therapist does not expect improvement, such as for those individuals receiving maintenance therapy, the modifier used for projected goal status will be the same as the one for current status.
Refer http://www.cms.gov/Outreach-and-Education/Outreach/NPC/Downloads/FunctionalReportingNPC.pdf for more information.
Also see 2013 Modifier Updates and List of all Modifiers