Understanding and navigating Medicare MUE, PTP edits

December 11, 2019

The Medicare National Correct Coding Initiative (NCCI) (also known as CCI) was installed to promote national correct coding methodologies and to control improper coding leading to payment. NCCI Procedure-to-Procedure (PTP) code pair edits are automated prepayment edits that prevent payment when certain codes are submitted together for Part B services.

In addition to PTP code pair edits, the NCCI includes a set of edits known as Medically Unlikely Edits (MUEs). An MUE is a maximum number of units allowable under most circumstances for a single CPT code billed by a provider on a date of service for a single beneficiary.

As with most CMS initiatives, it can be difficult to keep pace with the constantly evolving list of MUEs, especially when considering CMS and other carriers reserve the right to maintain a list of unpublished MUEs that providers and their billers likely won’t know about until they receive a denial.

It is important to understand, however, that the NCCI does not include all possible combinations of correct coding edits or types of unbundling that exist. Providers are obligated to code correctly even if edits do not exist to prevent use of an inappropriate code combination. Should providers determine that claims have been coded incorrectly, they are responsible to contact their Medicare Administrative Contractor (MAC) about potential payment adjustments.

Here is a quick breakdown for both PTP pair and MUE edits:

PTP Code Pair Edits    

1. PTP Edits-Practitioners These PTP code pair edits are applied to claims  submitted by physicians, nonphysician practitioners, and Ambulatory Surgery Center (ASCs).

2. PTP Edits-Hospital PTP edits are applied to Types of Bills (TOBs) subject to the Outpatient Code Editor (OCE) for OPPS. These edits are applied to outpatient hospital services and other facility services including, but not limited to, therapy providers (Part B Skilled Nursing Facilities (SNFs)), comprehensive outpatient rehabilitation facilities (CORFs), outpatient physical therapy and speech-language pathology providers (OPTs), and certain claims for home health agencies (HHAs) billing under TOBs 22X, 23X, 75X, 74X, 34X


1. Practitioner MUEs These edits are applied to all claims submitted by physicians and other practitioners.

2. Durable Medical Equipment (DME) Supplier MUEs These edits are applied to claims submitted to DME MACs. (At this time, this file will include HCPCS A-B and E-V codes in addition to HCPCS codes under the DME MAC jurisdiction.)

3. Facility Outpatient MUEs These edits are applied to all claims for TOB 13X, 14X, and Critical Access Hospitals (CAHs) [85X].

We were first gifted with MUEs when CMS implemented an unpublished MUE list in 2007 with hopes of reducing the error rate of paid claims. Fortunately, the agency decided to begin publicly publishing most MUEs in October 2008, and now updates the list quarterly.

It’s important to keep in mind that MUE limits are constantly evolving and are subject to significant shifts over time. It’s also worth reiterating that CMS and other carriers reserve the right to create unpublished MUEs, which means CMS’s published list is really more of a national guideline than a hard and fast rule.

Best practices for appealing edit denials:

However, an MUEs existence doesn’t prevent you from appealing to potentially receive full payment for all services provided. We work closely with our clients and their billers to make sure billers are appealing MUE denials and that our clients are getting paid on those appeals. But just because a denial is appealed doesn’t necessarily mean you’re going to get paid, especially if the physician’s documentation does not clearly substantiate the necessity of the number of units performed.

We have encountered some billers who just want to just slap on a 59 modifier to override the edit, but we’re finding more and more that these MUE edits are often not overridden with a 59 edit. You must support those numbers with sufficient documentation if they exceed the limit.

We’ve also seen billers who change the number of units to get around an MUE. Their argument is that the carrier will deny 100 percent of the charges otherwise, so they attempt to get paid on the maximum number of allowed units rather than none. That’s a major red flag in terms of compliance that could create headaches down the road later if you’re audited.

While we know many billers don’t want to dedicate the time and resources necessary for an appeal, they need to understand they must bill only what was performed. And if the carrier denies it, they have to go through the appeal process. It’s best to get a handle on that process now if you haven’t already so that you’re not left scrambling down the line.

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