Modifiers required for ASC.

ASC Billing Information for OWCP

Modifiers required for ASC.

Modifier –SG must be appended as the first modifier to all surgical procedure codes (CPT/HCPCS) billed by an Ambulatory Surgery Center. 

Modifiers accepted for ASC.

OWCP will accept all valid CPT and HCPCS modifiers, though only a few will affect payment.


Modifiers affecting payment for ASC.

Modifier -50, Bilateral modifier.

    Modifier -50 identifies cases where a procedure typically performed on one side of the body is performed on both sides of the body during the same operative session.  Providers must bill using a single line item for each procedure performed and append modifier  -50 to indicate that a procedure was performed bilaterally.  The bilateral procedure will be paid at 150% of the allowed amount for that procedure.

Example:  Bilateral Procedure, Modifier -50, Chicago, IL.

Line item    CPT code        Maximum    Bilateral policy    Allowed
  on bill      modifier         payment         applied         amount

    1    64721–SG–50        $1,090.08       $1.635.12            $1,635.12 
    Total allowed amount                                                   $1,635.12

1.  Bilateral procedure is paid at 150% of maximum allowed amount.


Modifier -51, Multiple surgerical procedures modifier, Chicago, IL.

    Modifier -51 identifies when multiple surgeries are performed on the same patient at the same operative session.  Providers must bill using separate line items for each procedure performed.  Modifier -51 should be applied to the second and subsequent line items.  The total payment equals the sum of
    100% of the maximum allowable fee for the highest valued procedure according to the fee schedule, plus
    50% of the maximum allowable fee for the subsequent procedures with the next highest values according to the fee schedule.

Example:  Multiple Procedure, Modifier -51, Chicago, IL.

Line item    CPT code        Maximum    Multiple procedures    Allowed
  on bill      modifier         payment    policy applied         amount

    1    29881–SG            $1,712.95                                               $1,712.95
    2    64721–SG–51     $1,090.08                    $545.04              $   545.04
    Total allowed amount                                                            $2,257.99

1.  Highest valued procedure is paid at 100% of maximum allowed amount.
2.  When applying the multiple procedure payment policy the secondary procedure billed with a modifier -51 is paid at 50% of the maximum allowed amount for that line item.
3.  Represents sum of allowed amounts for line 1 + line 2.

If the same procedure is performed on multiple levels the provider must bill using the proper number of units to indicate the number of levels.

Modifier -73, Discontinued procedure prior to the administration of anesthesia.

Modifier -73 is used when a physician cancels a surgical procedure due to the onset of medical complications subsequent to the patient’s preparation, but prior to the administration of anesthesia.  Payment will be at  50%  of the maximum allowable fee.  Multiple and bilateral procedure pricing will not apply.

Modifier -74, Discontinued procedure after administration of anesthesia.

Modifier -74 is used when a physician terminates a surgical procedure due to the onset of medical complications after the administration of anesthesia or after the procedure was started.  Payment will be at  85%  of the maximum allowable fee.  Multiple and bilateral procedure pricing may apply to this if appropriate to the circumstances.