Frequency Limit Denials and Modifiers: NCCI Edits, Telehealth and the ABN

Updated November 5, 2026, based on CMS, the Federal Register and the Code of Federal Regulations as of that date.

A frequency denial means the payer decided you billed a service too often, in too many units, or alongside a code it pays as part of another. On Medicare claims the decision comes from one of three places: a National Correct Coding Initiative (NCCI) edit, a coverage frequency limit on the benefit, or a billing rule for one code family, such as remote monitoring. The remit can look alike for all three, but the fix and who pays differ.

If an NCCI edit denied the line, you can't bill the Medicare patient, even with a signed Advance Beneficiary Notice (ABN). If a coverage frequency limit denied it and the patient signed a valid ABN before the service, you can. Modifiers decide many of these outcomes, so they belong on a claim only when the record supports them.

The rules below are Medicare fee-for-service rules unless noted.

Three kinds of edits produce frequency denials

Procedure-to-procedure (PTP) edits stop two codes from paying together. CMS's NCCI PTP edits page explains that when both codes in a pair are reported for the same patient on the same date, the Column Two code is denied unless a clinically appropriate NCCI PTP-associated modifier is reported. Per chapter 1 of the 2026 Medicare NCCI Policy Manual, a modifier indicator of "0" means no modifier can bypass the edit, and "1" means one can under appropriate circumstances.

Medically unlikely edits (MUEs) cap units. CMS's MUE page defines an MUE as the maximum units a provider would report for a code for one patient on one date on most correctly billed claims. The NCCI manual says an MUE with an adjudication indicator (MAI) of 1 applies per claim line, so a correct modifier can split units across lines. MAIs of 2 and 3 add up all units for the date. CMS tells contractors not to override an MAI 2 edit during processing, reopening or redetermination. Contractors can bypass an MAI 3 edit if the evidence shows the units were provided, correctly coded and medically necessary.

Coverage frequency limits, such as screening intervals, are set on the benefit itself through statute, regulation or coverage determinations.

CMS updates PTP and MUE files quarterly. Medicaid runs its own set. The Medicaid NCCI program page says state fee-for-service claims must use it, that using it in managed care plans is "desirable but optional," and that some Medicare edits are missing or different. Scrub Medicaid claims against the Medicaid files.

Remote monitoring device codes are billed once per 30-day period

Remote physiologic monitoring (RPM) denials usually involve the device supply codes. In the CY 2021 Physician Fee Schedule final rule, CMS said these services "can be billed by only one practitioner, only once per patient per 30-day period," and that the setup code, 99453, is billed once per episode of care.

The CY 2026 PFS final rule added 99445 for 2 to 15 days of data in a 30-day period, next to 99454 for 16 to 30 days. CMS said the two "are not additive": you bill one per 30 days, based on days of data. Treatment management works the same way. You pick 99470 (first 10 minutes) or 99457 (first 20 minutes) for the month, and 99458 can follow 99457.

CMS's Telehealth and Remote Monitoring booklet (MLN901705) adds that RPM needs an established patient and consent, that RPM and remote therapeutic monitoring (RTM) can't be billed together, and that either can be billed with chronic care management and similar services if time isn't counted twice.

More changes start January 1, 2027. CMS's CY 2027 PFS final rule fact sheet says it finalized RTM for established patients only, a separately reportable initiating visit at the start of RPM or RTM, and new valuation. A rule to pay only when the practice's employed staff do the work was delayed to CY 2029. Ask your MAC how it will check the initiating visit.

A device supply claim inside a 30-day period that's already been paid, including by another practitioner, can deny. Track each patient's periods and billing practitioner.

Screening limits and the colonoscopy after a positive stool test

Chapter 18 of the Medicare Claims Processing Manual lists the frequency rules for each preventive service. For example, Medicare covers a screening colonoscopy for a patient who isn't high risk (G0121) once at least 119 months have passed after the month of the last covered one.

Chapter 18 says that since January 1, 2023, the frequency limits for a screening colonoscopy (G0105, G0121) don't apply when it follows a positive non-invasive stool-based test. The practitioner shows this with the KX modifier on the colonoscopy claim. 42 CFR 410.37(k) now gives an effective date of January 1, 2025 and also covers a positive blood-based biomarker test. The manual's KX instruction names only stool-based tests, so ask your MAC how to bill after a blood-based test. Without KX, the claim can look like a second screening inside the interval. If a screening colonoscopy turns into a biopsy or removal, the manual says to bill the diagnostic code with the PT modifier instead of G0121.

Telehealth modifiers and place of service codes Medicare asks for

For Medicare professional claims, CMS's Telehealth FAQ says to use place of service (POS) 02 when the patient isn't at home and POS 10 when they are. Then add modifiers based on how the visit happened:

• Audio-only visits take modifier 93. Under 42 CFR 410.78(a)(3), audio-only telehealth to a patient at home is allowed when the practitioner can use video but the patient can't or doesn't consent. Rural health clinics (RHCs) and federally qualified health centers (FQHCs) can use FQ, which the CY 2025 PFS final rule calls identical in meaning.
• Modifier 95 is narrower on Medicare claims than many teams assume. The MLN901705 booklet lists it for outpatient therapy by hospital-employed therapists, and its professional billing section uses POS codes instead. Medicaid and commercial plans set their own rules for 95, so check each payer's policy.
• BB and BC are required from January 1, 2027, per the FAQ. BB marks telehealth delivered through a virtual platform the practitioner contracts with or pays to use. BC marks telehealth furnished incident to a practitioner's service. Neither changes payment.
• Since October 1, 2026, RHCs and FQHCs bill non-behavioral telehealth with the individual CPT or HCPCS code and a telehealth modifier, instead of G2025.

The FAQ says the current flexibilities, including telehealth anywhere in the U.S. and audio-only at home, run through December 31, 2027. It also says remote monitoring and chronic care management aren't Medicare telehealth services, so the rules above aren't written for them.

Modifiers 25 and 59 need a distinct service behind them

Chapter 1 of the NCCI Policy Manual says a modifier "shall not be appended to a HCPCS/CPT code solely to bypass an NCCI PTP edit if the clinical circumstances do not justify its use."

Modifier 25 marks an evaluation and management (E/M) service as significant and separately identifiable from a same-day procedure. The manual applies it to minor procedures (000 or 010 global days) and XXX procedures. The E/M can share the procedure's diagnosis, but the decision to do a minor procedure is part of that procedure, not a separate E/M.

Modifier 59 is for distinct procedural services. Use XE, XP, XS or XU when one describes the situation, and 59 only when none does. Modifiers 22, 76 and 77 never bypass a PTP edit.

Adding 25 to every claim by hand runs against that rule, and it bypasses the edits meant to catch claims with no distinct service behind them. Telehealth modifiers need the same care. Tie each modifier to the record: a separate E/M note for 25, an audio-only visit and the patient's reason for 93, a separate session or site for 59 or an X modifier.

When you can bill the patient for a denied service

The Introduction to the 2026 NCCI Policy Manual says services denied by PTP edits "may not be billed to Medicare beneficiaries," and an ABN can't change that because the denial is about coding, not medical necessity. Chapter 1 says the same for MUEs. Those lines are write-offs or appeals, and appeals go to your MAC or QIC.

Frequency limits work differently. Chapter 30 of the Claims Processing Manual allows a routine ABN for any frequency-limited service, as long as the notice names the limit as the reason. Chapter 18's example is a screening Pap smear for a low-risk patient who had a covered one within two years: get an ABN and bill with GA.

CMS's booklet on advance written notices (MLN006266) defines the claim modifiers:

1. GA: you issued a required ABN and have it on file.
2. GZ: you expect a medical necessity denial and didn't get an ABN.
3. GX: you issued a voluntary ABN for a service Medicare never covers.
4. GY: the service is statutorily excluded or isn't a Medicare benefit.

In chapter 18's screening denial instructions, a GA line goes to the patient (group code PR) and a GZ line goes to the provider (group code CO). Chapter 30 adds that without a valid ABN when one was required, you generally can't collect and must refund what you collected. It also says ABNs aren't used for Medicare Advantage, so follow the plan's rules for those members.

Some services go on the facility's claim

Under SNF consolidated billing, most services for a patient in a covered Part A skilled nursing facility stay are billed by the SNF to its Part A MAC, not by whoever furnished them. Physician professional services and a short list of others are excluded. In a non-covered stay, only therapy falls under consolidated billing.

Scrubbing claims before submission

Most of these denials can be caught before the claim goes out:

1. Load the current quarter's PTP and MUE files for the claim type, and the Medicaid files for Medicaid claims.
2. Track what the edit files don't show: each patient's remote monitoring periods and billing practitioner, and the last date of each screening service.
3. Check each modifier against the record, and flag 25, 59 and telehealth modifiers with no supporting note.
4. Confirm a signed ABN is on file before adding GA, and never use one for an NCCI denial.
5. Send only flagged claims to a coder or auditor.

Teams do this with staff checklists, clearinghouse scrubbers, payer edit tools or automation. For what comes after a denial, see our guide to denial management, and for the steps before one, our guide to claims submission.

Frequently asked questions

Can I bill the patient for an MUE denial if they signed an ABN?

No. The NCCI Policy Manual treats MUE denials as coding denials, so an ABN doesn't shift liability to the patient. If you think the units were right, appeal to your MAC.

Can two practices bill remote monitoring for the same patient in the same month?

No. Medicare allows one practitioner per patient per 30-day period, so the second claim will likely deny. Ask the patient about other monitoring before enrolling them.

Why did a screening colonoscopy deny for frequency after a positive stool test?

It was probably billed without KX. Medicare doesn't apply the colonoscopy frequency limit after a positive stool-based test, but the claim has to show it with that modifier.

Catching frequency and modifier edits before claims go out?

Champ automates back-office claim work in payer portals, such as checking claims before submission and following up on denials. We set it up and run it, so your team sees only the finished results. If frequency limits and modifier rules are behind too many of your denials, learn more here.

This post is general information, not legal, compliance or billing advice. Rules vary by payer and change often, so confirm with your Medicare Administrative Contractor or the payer before acting. Champ is not affiliated with or endorsed by CMS or the other agencies and plans mentioned here.