CKD Staging and ESRD Billing Mistakes That Cost Nephrology Practices Money

CKD staging and ESRD billing mistakes made in 2026 have a second deadline in July 2027. That month, CMS reruns Medicare Advantage risk scores on 2026 dates of service, removes diagnoses that came only from audio-only visits, and adjusts January through June payments to match.

That rerun only counts diagnoses tied to a recorded visit, and every other payment tied to the CKD stage depends on what the note says.

See Which Payments Each CKD Code Controls

The stage code on your claim decides three things in 2026, the patient’s risk category for 2027, whether you can bill kidney education sessions, and whether the patient can align to a Kidney Care Choices entity. The table shows how each code plays out.

Code on the claim	2027 risk score	Kidney education	KCC alignment
N18.1, N18.2, N18.9	No CKD category	Not eligible	Not eligible
N18.30, N18.31	Stage 3 category	Not eligible	Not eligible
N18.32	Stage 3b category, same weight as stage 3	Not eligible	Not eligible
N18.4	Stage 4 category	Up to 6 sessions	Eligible
N18.5	Stage 5 category	Only inside KCC	Eligible
N18.6 with Z99.2	CMS’s separate ESRD model	Some patients, only inside KCC	Eligible on maintenance dialysis

Every row starts with a word in your assessment, and that word is where the first mistake begins.

1. Letting the Lab Value Stand In for the CKD Stage

A note that says only “CKD” next to a stage 4 eGFR gets billed as N18.9. The FY 2027 official guidelines, in effect since October 1, 2026, let coders use only the stage the provider writes, and they require a query when the record conflicts with itself.

• What it costs: N18.9 sits outside every CKD risk category, so the patient’s risk score carries nothing for kidney disease
• Where it hides: One visit can hold a stage in three places, the assessment line, a problem list entry carried forward, and a copied-forward history

The fix: Write the stage in words in every nephrology assessment, with 3a or 3b spelled out, since N18.3 alone isn’t a billable code. Update the problem list in the same step, and make the stage a required field in your CKD template.

A written stage only helps when it lands on a visit CMS will count, and 2026 changed which visits those are.

2. Restaging a Patient During an Audio-Only Call

A CKD stage you update during a phone visit in 2026 won’t count toward the patient’s 2027 risk score when every risk-adjustable line on that claim carries modifier 93 or FQ, the audio-only markers. That rule comes from CMS’s July 2026 memo and applies to all provider types. Payments for January through June 2027 come from CMS’s initial run, which still counts those audio-only diagnoses, so nothing looks wrong until the midyear rerun.

• What it costs: The patient’s 2027 risk score keeps the old stage, which matters when your Medicare Advantage contracts or shared savings run on those scores
• What else drops out: Diagnoses from plan chart reviews that aren’t linked to an encounter, except for patients who switch to a plan under another parent organization

The fix: Each month, pull claims billed with modifier 93 or FQ that changed a CKD stage, and restate that stage at the next video or in-person visit. CMS is also reissuing plans’ MAO-004 reports in November 2026 to show which audio-only diagnoses were dropped.

That restated stage 4 code does more than protect a risk score, because stage 4 also triggers a Medicare benefit of its own.

3. Keeping a Stage 4 Patient Coded as Stage 3

A stage 4 patient still coded N18.30 can’t be billed for any of the kidney education sessions Medicare Part B covers through the education benefit, up to six in total. Each session claim needs G0420 for one-on-one or G0421 for a group, N18.4, a referral, and a doctor, qualified non-doctor provider or qualifying rural provider teaching it.

• What it costs: Every session you could have billed, plus KCC alignment if your practice belongs to a Kidney Contracting Entity
• The limits: Six sessions is a lifetime total, the patient owes 20 percent coinsurance after the Part B deductible, and a patient who reaches stage 5 falls outside the standard benefit

The fix: Pull patients whose recent labs suggest stage 4 but whose last claim isn’t N18.4, and send those charts to the provider for a staging decision. Before scheduling sessions, check whether another office already billed some of the six.

The KCC Model changes the picture at the next stage. In 2026 it includes 74 entities serving patients in 40 states and DC, runs through December 31, 2027, and aligns each patient based on where they get most of their kidney care. The move from stage 5 to dialysis carries the next mistake.

4. Holding Onto N18.5 After Chronic Dialysis Starts

Once a patient is on chronic dialysis, N18.5 is the wrong code, since the FY 2027 code set excludes “stage 5 requiring chronic dialysis” from N18.5 and sends it to N18.6. When your note documents ESRD or chronic dialysis, these codes change together.

• N18.6 replaces N18.5, and a note listing both gets N18.6 alone
• Z99.2 is added for dialysis dependence
• I12.9 becomes I12.0, and I13 codes move to their stage 5 and ESRD versions
• When the monthly note documents hypertension or diabetes, the “code first” note on N18 puts I12.0 or E11.22 ahead of N18.6
• A transplant patient who still has CKD gets Z94.0 plus the current N18 stage, since CKD alone isn’t a transplant complication, and if the graft fails and dialysis resumes, the ESRD codes return so a KCC patient can realign

What it costs: A stale ‘CKD 5’ entry puts an excluded code on every monthly claim for that patient. CMS also scores dialysis patients under a separate ESRD risk model, so your diagnosis should match the dialysis status the rest of the record reports.

The fix: Write the first treatment date in the note, update the problem list that week, and add a claim edit that flags N18.5 on any patient with a monthly dialysis code. Patients dialyzing for acute kidney injury have no ESRD diagnosis, so they stay outside this switch.

Once N18.6 is on the claim, the procedure code next to it depends on a visit count, and that count has its own trap.

5. Counting the Wrong Visits Toward the Monthly Capitation Code

The monthly capitation payment (MCP) code for an adult dialyzing in a center depends on how many face-to-face visits count that calendar month. Code 90960 needs four or more, 90961 needs two or three, and 90962 covers one, and Medicare pays more at each higher tier. The patient’s age on the last day of the month picks the age band, and CMS transmittals set which visits count.

• Visits in hospital observation status or a skilled nursing facility count
• Inpatient visits never count
• One visit each month needs a documented hands-on exam of the vascular access site
• Partners or employees in your group can supply visits, and each counted visit needs a signed note

What it costs: A missing observation or nursing facility visit drops a month you earned to a lower tier. A counted inpatient visit, an unsigned note or a missing access exam bills a month the record can’t support, and that’s money a later review can take back.

The fix: Before the claim goes out, match the dialysis unit’s treatment calendar against signed notes, tag each visit by setting, and confirm the access exam has its own line.

Hospital stays add a second decision on top of the count.

6. Switching to Per-Day Codes for Every Hospital Stay

A mid-month hospital admission still allows the full monthly code when the complete assessment was done. CMS transmittal R3311CP reserves per-day codes 90967 to 90970 for unusual partial months, so if you furnished outpatient visits before or after the admission, bill the full monthly code at the tier those visits reached.

• Per-day codes fit a patient admitted before any complete assessment, transient patients, dialysis that stops after recovery or death, a transplant during the month, and part-month home dialysis
• Full-month home patients use 90963 to 90966, one rate by age with no visit tiers

What it costs: Per-day billing pays only for the days you list, in a month where the full code covered the whole month.

The fix: Make the complete assessment date a required field on the monthly encounter, so the biller can see whether it came before the admission.

That same assessment also decides who bills the month.

7. Billing the Month Under the Wrong Clinician

The monthly claim belongs to whoever did the complete assessment, set the plan of care and manages the patient, under CMS transmittal R2269CP. When that clinician is an NP or PA, the claim goes under their number, and only one monthly claim goes out per patient even when several clinicians in your group see the patient.

What it costs: A claim under a clinician who didn’t do the complete assessment doesn’t match the record, so a review can take back the whole month. A second monthly claim from your group is also denied as a duplicate.

The fix: Record the assessing clinician on the monthly encounter and route the claim from that field.

The month’s claim also blocks codes a new dialysis patient may already be carrying.

8. Billing CCM or a Routine Visit in a Dialysis Month

Chronic care management can’t be billed in any calendar month that carries a code from 90951 to 90970, and a separate office visit that month pays only for a problem unrelated to ESRD that the note names. A CGS notice from September 8, 2026 reports a rise in provider questions about CCM billing and points billers to CMS’s CCM fact sheet, which lists this restriction.

What it costs: CCM time your staff logged before dialysis started that month can’t be billed once the monthly code goes out. CCM from the month before still bills normally, since the conflict runs one calendar month at a time.

The fix: Take the patient off the CCM roster as soon as a dialysis start date is set.

Fix CKD Staging and ESRD Billing Before the 2026 Books Close

CMS builds the risk scores it pays in the second half of 2027 from 2026 dates of service, so a stage you correct in January 2027 comes too late to count. That gives the CKD fixes a hard deadline of December 31, 2026, while the dialysis fixes belong in every month-end close.

• In November 2026: If you hold Medicare Advantage risk contracts, ask each plan for the reissued MAO-004 reports and look for dropped audio-only kidney diagnoses
• By December 31, 2026: Have providers restate the stage in words, at an in-person or video visit, for every patient whose 2026 claims show only N18.9, or a stage change made only on an audio-only call
• This month (October): Send every stage 4 patient with no G0420 or G0421 claim to the provider for an education referral decision
• Every month before claims go out: Confirm each dialysis patient carries N18.6 and Z99.2, each counted visit has a signed note and setting, one visit documents the access exam, the assessing clinician is on the claim, and no CCM code sits in the same month

An EHR that keeps the eGFR trend, problem list, visit log and dialysis schedule in one chart can flag each of these before the claim goes out. The OmniMD team can show you that workflow in a demo, and our nephrology codes list keeps the current N18 and dialysis codes in one place.