CMS Pub. 100-04, ch. 1, § 120.1

The claims processing systems contain edits which identify exact duplicate claims and

suspect duplicate claims. All exact duplicate claims or claim lines are auto-denied or

rejected (absent appropriate modifiers). Suspect duplicate claims and claim lines are

suspended and reviewed by the claims administration contractors to make a

determination to pay or deny the claim or claim line.

Some claims that appear to be duplicates are actually claims or claim lines that contain an

item or service, or multiple instances of an item or service, for which Medicare payment

may be made. Correct coding rules applicable to all billers of health care claims

encourage the appropriate use of condition codes or modifiers to identify claims that may

appear to be duplicates, but, in fact, are not.

For example, there are some HCPCS modifiers that are appropriate to be appended to

some services and can indicate that a claim line is not a duplicate of a previous line on the

claim. Level I modifiers would typically be used by a biller to indicate that a potential

duplicate claim or claim line is not, in fact, a duplicate. Level II modifiers may also be

used. The Level II modifiers “RT” and “LT”, for example, indicate that a service was

performed on the right and left side of the body, respectively.

However, not every HCPCS code has an associated modifier to indicate that a claim line

is not a duplicate. In that case, the claims and claim lines are reviewed by Medicare

contactors’ local software modules for a determination or they suspend for contractor

review.