What Happens When a Medicare CPAP Patient Fails the 90 Day Trial?

Updated November 2026. Written by Matteo Grassi, clinical psychologist and cofounder of HANA Health.

When a Medicare CPAP patient fails the 90 day trial, continued coverage stops after month three. The supplier can't add the KX modifier to month four claims, and the patient needs a new in person evaluation plus a repeat facility based Type I sleep study before a second trial can begin. The adherence standard is 4 hours a night on 70% of nights in a 30 day window.

Clinically, a failed trial often has a fixable cause, like a leaking mask, and the repeat evaluation exists to find it.

Key facts

• The standard: use of 4 or more hours per night on 70% of nights during a consecutive 30 day period within the first 3 months, per LCD L33718.
• The visit: an in person re-evaluation between day 31 and day 91 that documents improved OSA symptoms, with adherence data reviewed by the treating practitioner (LCD L33718, revision effective 1 January 2024).
• If criteria aren't met: continued coverage of the device and accessories is denied as not reasonable and necessary (LCD L33718).
• KX modifier: on month four and later claims, only if both the initial and continued coverage criteria are met, per Policy Article A52467.
• Requalifying: an in person re-evaluation plus a repeat facility based Type I study, which can be diagnostic, titration or split night (LCD L33718).
• Second trial billing: the DME MACs say suppliers may not bill with KX during the new 12 week trial, in a joint DME MAC article from 2019, updated 2021.
• Real world pattern: 48% of 213,341 commercially insured patients met the CMS criteria in all four 90 day quarters of year one, and 22% met them in none (Alpert et al., Chest, 2024).

What exactly counts as failing the 90 day trial?

A patient fails when the record can't show both halves of the continued coverage test by the end of the trial. Half one is an in person visit between day 31 and day 91 where the practitioner documents that OSA symptoms improved. Half two is objective usage data, reviewed by that practitioner, showing the adherence standard was met.

The standard is easy to misread, so run the arithmetic. Seventy percent of a 30 day window is 21 nights.

• Window A: 22 nights at 4 or more hours out of 30 is 73%. The patient meets the standard.
• Window B: 19 nights at 4 or more hours out of 30 is 63%. The patient misses it.
• Any window counts: the test says "a consecutive 30 day period anytime during the first 3 months," so check every 30 day stretch, not only days 61 to 90.

A patient who used the machine all night, every night, but only for 3 hours doesn't qualify. A patient who had a great second month and a rough third still can. Our Medicare CPAP compliance guide walks through the full test, and the reevaluation guide covers what the visit has to document.

What happens to the fourth month claim when the criteria aren't met?

Month four can still be submitted, but the KX modifier can't be on it. Policy Article A52467 says that on the fourth month's claim and any month after, the supplier adds KX only if both the initial and continued coverage criteria are met. If the supplier doesn't get the practitioner's information in time, it may still submit, but KX must not be added.

Suppliers have a second option: hold the claims. If the records later show a re-evaluation between day 31 and day 91 with improvement and adherence, the held claims can go out with KX. If the re-evaluation happened after day 91 but showed benefit and adherence, KX applies only to dates of service after that re-evaluation.

When the trial has truly failed, the LCD is plain. Continued coverage of the device and related accessories is denied as not reasonable and necessary. The joint DME MAC article adds that KX billing stops after month three if the initial trial fails.

Can a patient who fails the trial get Medicare coverage again?

Yes. A failed trial isn't permanent. LCD L33718 says beneficiaries who fail the initial 12 week trial can requalify, and the DME MACs lay out the sequence.

1. In person re-evaluation. The treating practitioner examines the patient to determine why therapy failed. This is a clinical question about mask fit, pressure, comfort or something else.
2. Repeat facility based sleep study. It must be a Type I study. The LCD says it may be a repeat diagnostic, titration or split night study.
3. New 12 week trial. It starts only after steps one and two. The DME MACs say suppliers may not bill with KX during this trial.
4. Second re-evaluation. The practitioner documents benefit and objective adherence. Only then can KX billing resume, which in the 13 month capped rental cycle means the fourth claim.

The practical effect is a gap. The patient does real work, a visit and an overnight lab study, and the supplier carries a rental period it can't bill with KX. Our guide to the 13 month capped rental shows how that cycle fits together.

Who pays while the patient requalifies?

It depends on notice. When a supplier expects Medicare to deny an item as not reasonable and necessary, CMS's tool for shifting liability to the patient is the Advance Beneficiary Notice of Noncoverage, or ABN. The Medicare Learning Network booklet on advance written notices lists items that aren't reasonable or necessary as a core use.

Without a valid written notice, the supplier is generally presumed to know the item wouldn't be covered, and it carries the liability unless it can show it couldn't reasonably have known. That standard appears in Chapter 30 of the Medicare Claims Processing Manual.

Here's the catch for CPAP. The LCD tells suppliers that if a patient stops using the device at any time, the supplier is expected to find that out and stop billing for the equipment and supplies. Billing a patient who quit months ago isn't a gray area.

Talk to your compliance lead about when and how your team issues an ABN. The right moment is before the care happens, not after the denial arrives.

What if the patient was late rather than non adherent?

Many "failures" are paperwork misses. The patient used the machine, but the visit happened on day 95. The LCD handles this: if the re-evaluation comes after day 91 and shows benefit and adherence, continued coverage starts on the date of that re-evaluation. Days in between aren't covered.

Switching devices has its own clock. If an E0601 CPAP is tried and found ineffective, substituting an E0470 bilevel doesn't change the trial length unless fewer than 30 days remain. With fewer than 30 days left, the re-evaluation and adherence documentation must happen before the 120th day after the E0601 started. If an E0601 was used more than 3 months before the switch, the clock restarts: the re-evaluation falls between day 31 and day 91 of the E0470, with a new 3 month trial.

A patient who shows up on day 40 with 25 good nights is on track, and a missed day 91 deadline isn't a clinical failure. It's a scheduling one, and it's the cheapest kind to prevent.

How common is it to miss the standard?

Common enough to plan around. In a study of 213,341 commercially insured patients with OSA, 48% met an extension of the CMS criteria in all four 90 day quarters of year one, 30% met it in one to three quarters, and 22% in none (Alpert et al., Chest, 2024).

The limits matter. The patients were commercially insured adults aged 18 to 64, not Medicare beneficiaries, and the study measured device use quarter by quarter rather than the single trial window Medicare uses. It doesn't tell us what share of Medicare patients fail the first trial.

What it does show is that adherence drifts, even among people who got a device and started therapy. Our day by day 90 day outreach plan is built around catching that drift before day 91.

What this means for your DME

Treat day 91 as a deadline you manage from day one. Practical steps:

• Pull usage data weekly and flag anyone who can't reach 21 qualifying nights in any 30 day window.
• Book the day 31 to 91 visit before dispensing, and confirm the date at week four.
• Send the practitioner the usage report in a written form they can review and place in the chart.
• Decide in advance whether you hold month four claims or submit without KX, and apply that rule consistently.
• Document every attempt to reach a struggling patient, including mask changes offered.
• Check with your compliance lead on ABN timing before month four, not after.

HANA runs check in calls and texts through the first 90 days so coaches can see who's falling behind and clinicians make the decisions. You can see how it works on the HANA sleep page.

Frequently asked questions

Can a different practitioner do the day 31 to 91 visit?

Yes, according to Noridian's clinician guidance on PAP devices. It says the re-evaluation doesn't have to be done by the practitioner who ordered the device, and another physician or non physician practitioner following the patient can do it.

Can a supplier submit month four without the KX modifier?

Yes. Policy Article A52467 says that if the supplier doesn't have the information in time, it may still submit the claim, but KX must not be added. Expect the claim to be denied if the continued coverage criteria weren't met.

Does a switch from CPAP to bilevel give the patient extra time?

Sometimes. If fewer than 30 days remain in the trial when an E0470 replaces an E0601, the re-evaluation and adherence documentation must come before day 120. If more than 30 days remain, the original day 31 to 91 window still applies.

Do commercial payers run the same 90 day trial?

Not uniformly. Commercial rules vary by plan, and the Chest study describes US commercial PAP coverage rules as nonstandardized. Our post on commercial payer adherence rules compares examples.

What if a patient stops using CPAP mid rental?

The LCD says the supplier is expected to ascertain that and stop billing for the equipment, accessories and supplies. Documenting your outreach attempts protects you if a claim is ever reviewed.

Sources

1. Centers for Medicare & Medicaid Services. Local Coverage Determination L33718, Positive Airway Pressure (PAP) Devices for the Treatment of Obstructive Sleep Apnea. Revision effective 1 January 2024.
2. Centers for Medicare & Medicaid Services. Policy Article A52467, Positive Airway Pressure (PAP) Devices for the Treatment of Obstructive Sleep Apnea.
3. Noridian Healthcare Solutions, Joint DME MAC article. Correct Billing, Continued Coverage for PAP Devices. Published 2019, updated 2021.
4. Noridian JD DME. Clinicians! Are You Ordering PAP Devices and Related Accessories for Your Patients?
5. Centers for Medicare & Medicaid Services, Medicare Learning Network. MLN006266, Medicare Advance Written Notices of Non-coverage.
6. Centers for Medicare & Medicaid Services. Medicare Claims Processing Manual, Chapter 30, Financial Liability Protections.
7. Alpert N, Cole KV, Dexter RB, Sterling KL, Wickwire EM. Performance of Claims-Based Algorithms for Adherence to Positive Airway Pressure Therapy in Commercially Insured Patients With OSA. Chest, 2024.

This article is educational and isn't billing, coding, clinical or legal advice. Check current CMS guidance and your MAC before you bill.

If you run a DME and want to talk through your first 90 days, book a discovery call.