Modifiers are an integral part of coding, used to indicate that some specific circumstance altered a service or procedure you performed, but didn't change its definition or code. Modifiers not only expand the information CPT codes provide, but payers also rely on them to maintain their claims and underwriting databases. Here are the six most common modifier errors we've uncovered in coding audits.

1. Using modifiers with unlisted
procedure codes. Since unlisted codes don't include descriptor language that specifies the components of a particular service, there's no need to alter the meaning of the code. Further, the American Medical Association says it's not appropriate to append modifiers to unlisted procedure codes. This excludes any carrier-specific modifiers, such as the ?SG for Medicare, or any contractually mandated modifiers.

Per the AMA CPT Assistant, April 2001, "when performing two or more procedures that require the use of the same unlisted code, the unlisted code used should only be reported once to identify the services provided. This is due to the fact that the unlisted code does not identify a specific unit value or service. Unit values are not assigned to unlisted codes since the codes do not identify usual procedural components or the effort/skill required for the service."

2. Using the Medicare required modifier ?SG on non-Medicare claims.
You should only use this modifier for Medicare claims. Depending on the payer's claim processing software, doing otherwise could cause denials or delays in payment. Importantly, since many billing programs only accommodate two modifiers, it may cause another more important modifier to be bumped off the claim. Keep in mind that the ?SG modifier should not be appended to HCPCS level two codes, such as implants, when submitting to Medicare. If Medicare is the secondary payer, you can add the ?SG at the time the secondary claim is printed. Then the biller can verify the medical necessity requirements that apply specifically to Medicare in the form of Local Coverage Determinations and Local Medicare Review Policies before the claim is submitted.

3. Appending site-specific modifiers to multiple-site CPT codes.
Don't append laterality modifiers (?LT, ?RT), the bilateral modifier (?50) and site-specific modifiers (for example, E1, T1, F1) to procedure codes that include different anatomical sites in their description, such as the lesion excision and repair codes (for example, "13150 - Repair, complex, eyelids, nose, ears and/or lips; 1.0 cm or less").

4. Using the multiple-procedure modifier in an ASC.
The ?51 modifier is not an approved ASC modifier per CPT 2005, Appendix A. This modifier is a physician modifier and is used to indicate when the same provider performs multiple procedures, other than evaluation and management services, at the same session. Only use this modifier if it's required in writing by a carrier or is contractually mandated.

5. Using toe and finger modifiers instead of foot and hand modifiers.
Another common error coders make is applying toe or finger modifiers when laterality modifiers would be more appropriate. Anatomically, metacarpals are bones of the hand and metatarsals are bones of the foot, so coding ?RT or ?LT for laterality would be more appropriate than a modifier for an individual finger or toe. Keep in mind that, when procedures are performed on the phalanx or phalanges, it is correct to report the finger or toe modifier.

6. Failing to report modifiers on the UB-92.
Are you reporting your modifiers on the UB-92 (HCFA-1450) claim form? Not doing so may cause a loss of revenue and unnecessary denials. There is space for two modifiers in box 44 next to the CPT code. If these aren't being carried over to your claim form, ask your billing software vendor for help.