Modifier 99- Multiple Modifiers

Identifies a service or procedure that requires multiple modifiers when all applicable modifiers cannot be accommodated in the standard modifier fields of the claim.

What Is Modifier 99?

Modifier 99 identifies multiple modifiers associated with the same CPT or HCPCS service.

A single service can sometimes require several modifiers to accurately communicate the circumstances under which it was performed. These modifiers may describe the provider's role, anatomical location, professional or technical component, payment circumstances, or other relevant information.

Modifier 99 functions differently from most modifiers because it does not describe a clinical circumstance by itself. Instead, it signals that additional modifiers apply to the reported service and must be communicated according to the payer's claim-submission requirements.

CMS guidance recognizes Modifier 99 for reporting multiple modifiers when the available claim fields cannot accommodate all applicable modifiers.

When to Use Modifier 99

Multiple Modifiers Apply: The same CPT or HCPCS service legitimately requires several modifiers to accurately describe the service.

Available Fields Are Insufficient: The claim format does not provide enough modifier positions for all required modifiers.

Payer Allows Modifier 99: The applicable Medicare Administrative Contractor or other payer instructs providers to use Modifier 99 when additional modifiers must be reported.

Additional Modifiers Are Reported Elsewhere: The actual modifiers represented by Modifier 99 are supplied in the appropriate claim field, remarks section, or electronic equivalent.

Modifier Requirements Are Independently Met: Every modifier represented by Modifier 99 must be supported by the service performed and applicable billing rules.

When NOT to Use Modifier 99

Available Modifier Fields Are Sufficient: If all applicable modifiers can be reported normally, Modifier 99 generally isn't necessary.

Only One Modifier Applies: Modifier 99 should not be used simply to indicate that a service has a modifier.

Modifier Is Unknown: Do not use Modifier 99 as a substitute when the correct modifier has not been determined.

To Bypass Claim Edits: Modifier 99 does not override NCCI edits, coverage policies, medical necessity requirements, or other Medicare payment rules.

Unsupported Modifiers: Do not use Modifier 99 to report additional modifiers that aren't supported by the documentation.

Payer Requires Another Method: Claim formats and payer instructions can differ. Follow the applicable payer's current requirements for reporting multiple modifiers.

Billing Example

A provider performs a service for which several legitimate modifiers apply.

The modifiers describe different aspects of the same service, but the applicable claim format does not provide enough modifier positions to report all of them normally.

When permitted by the payer, the provider reports Modifier 99 in the appropriate modifier field and supplies the actual additional modifiers in the required remarks or supplemental claim field.

For Medicare claims where Modifier 99 is used, the additional applicable modifiers must still be identified. Modifier 99 is not a replacement for determining or documenting those modifiers. CMS guidance specifically instructs providers to report the applicable modifiers when 99 is used.

Documentation Requirements

Underlying Service: Documentation must support the CPT or HCPCS code reported.

Each Modifier: The medical record should support the circumstances represented by every applicable modifier.

Multiple-Modifier Need: Claim information should establish which modifiers apply to the individual service line.

Modifier Sequence: Follow applicable payer instructions concerning modifier placement and sequencing.

Supplemental Information: When Modifier 99 requires additional modifiers to be reported elsewhere on the claim, provide that information in the required field.

Medical Necessity: Modifier 99 does not replace documentation supporting the medical necessity of the underlying service.

Billing and Claim Considerations

Modifier 99 should be used as a claim-reporting mechanism, not as a shortcut for modifier selection.

The first step is determining which modifiers actually apply to the service. Only after those modifiers have been established should the provider determine whether the claim format has enough available positions to report them.

CMS guidance demonstrates this distinction clearly. Modifier 99 indicates multiple modifiers, while the actual applicable modifiers still have to be communicated on the claim.

Current CMS billing guidance can also vary by claim context. For example, a current Medicare coverage article instructs providers that when five or more modifiers apply, Modifier 99 should be reported in Item 24D and the modifiers listed in Item 19 or the electronic equivalent.

Providers should therefore follow the current instructions applicable to their claim format and Medicare Administrative Contractor rather than assuming that Modifier 99 is required whenever several modifiers apply.

Modifier 99 and Electronic Claims

Electronic claims can accommodate multiple modifier values directly, making Modifier 99 unnecessary in many situations.

Older CMS guidance notes that electronic professional claim transactions can provide multiple modifier positions. This illustrates why Modifier 99 should not automatically be appended simply because more than one modifier applies.

Billing systems may also handle additional modifiers differently. Providers should verify how their clearinghouse, practice-management software, payer, and current electronic transaction format expect multiple modifiers to be transmitted.

The goal is to communicate the actual modifiers accurately, not merely to place Modifier 99 on the claim.

Modifier Sequencing Matters

When multiple modifiers apply, correct modifier selection is only part of the billing process. Modifier sequencing may also affect claim processing.

Different modifiers communicate different types of information. Depending on the payer and service, some modifiers may affect payment while others provide informational, anatomical, or service-specific details.

Modifier 99 does not determine the correct sequence.

Providers should establish every applicable modifier first and then follow current payer guidance for ordering and reporting them. A clearinghouse accepting a claim does not necessarily mean the modifier combination or sequence is correct for payment.

Modifier 99 and NCCI Edits

Modifier 99 should not be confused with an NCCI PTP-associated modifier.

Medicare's NCCI Procedure-to-Procedure edits prevent inappropriate payment for code combinations that generally should not be reported together. Certain edits may be bypassed only when a clinically appropriate NCCI-associated modifier is supported.

Modifier 99 does not independently establish that two services are distinct.

If Modifier 59, XE, XP, XS, XU, or another appropriate modifier is necessary to address an NCCI edit, the documentation must support that specific modifier. Reporting Modifier 99 does not replace those requirements.

Common Billing Mistakes

Using 99 Whenever Two Modifiers Apply: Multiple modifiers can often be reported directly without Modifier 99.

Failing to Report the Actual Modifiers: Modifier 99 signals multiple modifiers but does not eliminate the need to identify them according to payer instructions.

Using 99 as a Placeholder: Modifier 99 should not substitute for researching which modifiers actually apply.

Incorrect Modifier Combination: Each additional modifier must independently satisfy its reporting requirements.

Incorrect Sequencing: Multiple modifiers may be valid individually but submitted in an order inconsistent with payer processing requirements.

Trying to Override an NCCI Edit: Modifier 99 does not establish that services qualify for separate payment.

Ignoring Claim-Format Requirements: Paper and electronic claims may handle multiple modifiers differently.

Assuming All Payers Follow Medicare: Commercial and Medicaid plans may have different rules for reporting multiple modifiers.

Common Denial Reasons

Additional Modifiers Missing: Modifier 99 is reported without the actual modifiers or supplemental information required by the payer.

Incorrect Modifier Combination: One or more of the reported modifiers do not apply to the service.

Modifier Sequence Incorrect: The payer expects the modifiers to be submitted in a different order.

Documentation Does Not Support Modifiers: The medical record does not substantiate the circumstances represented by one or more modifiers.

Modifier 99 Not Required: The claim format provides sufficient space to report the applicable modifiers directly.

NCCI Requirements Not Met: The claim uses multiple modifiers but does not contain a clinically appropriate modifier supported by documentation for the applicable edit.

Payer-Specific Requirements Not Followed: The claim does not comply with the insurer's multiple-modifier reporting instructions.

Modifier 99 vs. Modifier 59

Modifier 99: Indicates that multiple modifiers apply to a service when they cannot all be accommodated through the normal modifier reporting fields.

Modifier 59: Identifies a distinct procedural service when the circumstances satisfy applicable reporting and NCCI requirements.

These modifiers serve fundamentally different purposes.

Modifier 59 communicates a specific circumstance affecting a service, while Modifier 99 is primarily a mechanism for communicating that multiple modifiers apply.

Modifier 99 should never be used as a substitute for Modifier 59 when Modifier 59—or a more specific X{EPSU} modifier—is required.

Frequently Asked Questions

Does Modifier 99 replace the other modifiers that apply to a service?
No. Modifier 99 indicates that multiple modifiers apply, but the actual modifiers must still be identified according to the payer's claim-submission instructions. CMS guidance specifically requires the applicable modifiers to be supplied when Modifier 99 is reported.

Should Modifier 99 be used every time a claim has several modifiers?
No. Use the available modifier fields first and follow the payer's current reporting instructions. Modifier 99 becomes relevant when the applicable modifiers exceed what the claim format or payer's normal reporting method can accommodate.