CPT Codes 90935 & 90937: Complete Hemodialysis Billing Guide, Documentation, Reimbursement & Coding Rules (2026)

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Hemodialysis billing is high stakes. With Medicare scrutiny of dialysis claims intensifying in 2026 and commercial payers tightening their documentation standards, the margin for billing error in nephrology has never been narrower. CPT codes 90935 and 90937 the two core per-session hemodialysis codes are among the most frequently miscoded and most frequently denied dialysis billing codes in the country.

The difference between these two codes comes down to physician involvement during the hemodialysis session itself: one evaluation or multiple evaluations with active management. That distinction sounds simple. In practice, it is where billing teams consistently make costly mistakes either billing 90937 without documentation to support multiple evaluations, or billing 90935 when the clinical record actually justified the higher-intensity code.

Our nephrology billing specialists at MedCloudMD work with dialysis centers and nephrology practices across the country to get these codes right. This guide walks you through everything your billing team needs: code definitions, clinical scenarios, documentation requirements, billing workflows, Medicare rules, common denial patterns, and compliance safeguards

all in one place, updated for 2026.

💡  Did You Know?

CPT 90935 and 90937 are per-session hemodialysis codes they are billed per dialysis treatment, not per month. This makes them fundamentally different from the ESRD monthly capitation codes (90960–90962). Confusing these two code families is one of the most common and most expensive errors in nephrology billing. Using a monthly capitation code when a per-session code applies, or vice versa, creates denials, compliance exposure, and delayed reimbursement that can be difficult to recover from.

01 — What Are CPT Codes 90935 and 90937?

CPT 90935 and 90937 are both per-session hemodialysis procedure codes. They cover the physician's clinical involvement during an individual hemodialysis treatment not a month's worth of ESRD management, but a single dialysis session. Both codes are billed per treatment and apply when a physician or other qualified healthcare professional (OQHCP) is actively involved in managing the patient during the dialysis session.

CPT 90935 — Single Physician Evaluation

CPT 90935 is defined as: Hemodialysis procedure with single evaluation by a physician or other qualified health care professional. This code is used when the physician evaluates the patient once during the hemodialysis session. The evaluation may include a clinical assessment, review of the patient's response to treatment, management orders, and documentation of the encounter. The patient is typically stable enough that one evaluation is sufficient to manage the session appropriately.

CPT 90937 — Multiple or Intensive Physician Evaluations

CPT 90937 is defined as: Hemodialysis procedure requiring physician or other qualified health care professional evaluation(s) with patient management during hemodialysis, with or without substantial revision of the dialysis prescription. This code applies when the patient's clinical condition during the session requires more than a single evaluation either because complications arise, the patient is hemodynamically unstable, or the dialysis prescription requires active revision based on the physician's repeated clinical assessments during the treatment.

🔑  Core Distinction in Plain Terms

CPT 90935: Physician evaluates the patient ONCE during the hemodialysis session. Patient is generally stable. One clinical assessment supports the claim.

CPT 90937: Physician evaluates the patient MULTIPLE TIMES or manages an actively evolving clinical situation during the session. Documentation must reflect each evaluation and the clinical reasoning behind repeated physician involvement.

02 — CPT 90935 vs CPT 90937: Side-by-Side Comparison

The table below provides a direct comparison of both codes across every billing-relevant dimension. Use this as a quick reference for your billing and coding team.

03 — When Should CPT 90935 Be Reported?

CPT 90935 is the appropriate code when a physician or OQHCP provides a single evaluation during a hemodialysis session. The clinical picture that supports this code is a patient whose treatment proceeds as planned, without intra-session complications that require the physician to return for repeated assessment.

Clinical Scenarios Appropriate for CPT 90935

Billing Tip — CPT 90935: When selecting 90935, the clinical note must clearly reflect that the physician's single evaluation was sufficient to manage the patient for the entire treatment session. If complications arose during the session that required the physician to return, 90935 is no longer appropriate — the documentation should be reviewed for whether 90937 is better supported.

04 — When Should CPT 90937 Be Reported?

CPT 90937 applies when the clinical situation during the hemodialysis session demands that the physician return for additional evaluation(s) or actively manages a patient whose condition changes during treatment. The key differentiator is not the severity of the patient's underlying diagnosis it is what happened during the actual hemodialysis session that required repeated physician presence and management.

Clinical Scenarios Appropriate for CPT 90937

🚨  Warning — Billing CPT 90937

CPT 90937 is one of the highest-scrutinized hemodialysis codes in nephrology billing. Billing 90937 when the documentation reflects only a single physician evaluation regardless of diagnosis complexity is upcoding. The clinical record must show that the physician evaluated the patient on at least two separate occasions during the session, OR that active management was required that substantially altered the course of the treatment. Diagnosis severity alone does not justify 90937.

05 — Documentation Requirements for CPT 90935 & 90937

Documentation is the entire basis of your claim for both 90935 and 90937. No payer Medicare or commercial will sustain a hemodialysis claim where the clinical record does not specifically support the code level billed. The checklist below reflects what our billing team verifies before submitting any 90935 or 90937 claim in 2026.

 06 — Step-by-Step Billing Workflow for CPT 90935 & 90937

01	Patient Encounter & Session Initiation  — Confirm hemodialysis session is occurring, physician or OQHCP involvement is documented from the start, and the clinical basis for hemodialysis (AKI, acute ESRD management) is established in the record
02	Real-Time Documentation of Evaluations  — Physician documents each evaluation during the session with time-stamped notes. For 90935: one evaluation note is required. For 90937: every additional evaluation and clinical management decision must be recorded individually as it occurs
03	Intra-Session Event Capture  — Any complications, hemodynamic changes, access issues, or prescription revisions must be documented at the time they occur — not reconstructed afterward. Contemporaneous notes are the standard that withstands audit
04	Code Selection at Session Close  — After the session is complete, review all documentation: if one evaluation occurred → CPT 90935. If multiple evaluations or active intra-session management with prescription change → CPT 90937. Code matches documentation not clinical intuition
05	Medical Necessity Validation  — Confirm that the selected diagnosis code(s) support the medical necessity for hemodialysis at the billed code level. ICD-10 must be present in the clinical record and logically connected to the CPT code selected
06	Modifier Review  — Assess whether any modifiers are required: -25 if a separately identifiable E/M was performed same day; -76 if same procedure repeated by same physician on the same day (rare, verify with payer); -59 for distinct procedural service when applicable
07	Eligibility & Authorization Verification  — Confirm active coverage for the date of service. Some commercial payers require prior authorization for hemodialysis — verify before claim submission to avoid authorization-related denials
08	Claim Construction & Scrubbing  — Build the claim with CPT code, ICD-10 primary and secondary diagnoses, POS (21 for inpatient, 22 for outpatient hospital, 65 for ESRD facility), and rendering provider NPI. Run through claim scrubbing software before submission
09	Electronic Submission & Tracking  — Submit electronically via clearinghouse. Confirm acceptance and track claim status actively from submission through initial payer response
10	Payment Posting & Variance Analysis  — Post payment and compare against expected reimbursement. Flag underpayments. Identify any contractual variances for commercial payer claims
11	Denial Management  — Route denied claims for appeal within 5 business days. Analyze denial reason codes documentation-related denials for 90937 are the most common and require the strongest clinical record in the appeal package

07 — Medicare Billing Guidelines for CPT 90935 & 90937 (2026)

Medicare is the dominant payer for dialysis services in nephrology. Understanding how CMS expects 90935 and 90937 to be billed and documented is foundational to maintaining a compliant and financially healthy nephrology billing operation.

Section 7: Common CPT 90970 Billing Errors & Denial Prevention

The billing errors we correct most frequently on CPT 90970 claims fall into predictable categories. Recognizing these patterns and building workflows that prevent them is the fastest way to improve your clean claim rate on partial-month ESRD billing.

08 — Commercial Insurance Considerations

Commercial payers follow their own policies for hemodialysis billing, and those policies do not always mirror Medicare's rules. Before submitting any CPT 90935 or 90937 claim to a commercial payer, your billing team should verify the following:

09 — Common Billing Errors & How MedCloudMD Prevents Them

These are the billing errors our team corrects most frequently on 90935 and 90937 claims when we conduct revenue cycle assessments for new nephrology billing clients. Many have been recurring for months before anyone identifies them.

10 — Reimbursement Factors for CPT 90935 & 90937

We do not publish specific reimbursement amounts for CPT 90935 or 90937 because Medicare rates are updated annually via the Physician Fee Schedule and vary by geographic location, payer type, and contracted rates. What we provide below is a framework for understanding what drives your actual payment on each claim.

Reimbursement Factor	Impact on Your Revenue
Code Level Billed	90937 carries a higher RVU assignment than 90935, reflecting the greater physician work and clinical intensity. Every session documented and coded accurately at 90937 when warranted represents meaningful per-session revenue difference over a month of dialysis billing
Geographic Adjustments (GPCI)	CMS adjusts payment via the Geographic Practice Cost Index based on your practice location. Work, Practice Expense, and Malpractice RVU components are each GPCI-adjusted, producing different effective rates across regions
Physician Fee Schedule Updates	The annual PFS conversion factor is updated each January 1. 2026 rates may differ from 2025 rates — verify current year RVU values and the conversion factor for both 90935 and 90937 to support accurate revenue forecasting
Commercial Contract Rates	Commercial payers set their own rates, often as a percentage of Medicare. Contract terms for nephrology services should be reviewed and renegotiated periodically — below-market contracted rates on per-session dialysis codes create systematic revenue leakage
Documentation Completeness	Incomplete documentation leading to downcoding or denial directly impacts reimbursement at the per-session level. In a practice with high dialysis volume, even a small percentage of documentation-related downcodes creates significant annual revenue loss
Facility Type	Reimbursement for the physician component differs depending on whether services are rendered in an inpatient hospital, outpatient hospital, or ESRD facility. Facility setting affects both POS and applicable physician payment rates
Coding Accuracy Rate	Practices with high first-submission clean claim rates receive faster payment and incur lower administrative costs per dollar collected. Every denial creates additional cost — improving coding accuracy is a direct revenue optimization strategy
Timely Filing Compliance	Claims filed past the payer's timely filing deadline are forfeited regardless of clinical accuracy. In per-session billing, delays in claim release compound across high-volume dialysis patient panels, creating material revenue loss

11 — Documentation Audit Checklist — Before Every Claim Submission

Every CPT 90935 or 90937 claim should pass this checklist before submission. This is the internal review standard our billing team uses for every nephrology client we support.

✅  Pre-Submission Audit Checklist — CPT 90935

✔  ONE complete, individually authored, dated and timed physician evaluation note is present in the record for this session

✔  The evaluation note documents: patient assessment, clinical findings, response to treatment, management decisions, and physician reasoning

✔  Dialysis treatment parameters (blood flow, UF goal, session duration) are documented

✔  ICD-10 primary diagnosis (AKI or ESRD) is supported by the clinical record and present on the claim

✔  POS code matches the actual treatment setting (21, 22, or 65 as applicable)

✔  Physician signature and authentication date are present on the evaluation note

✔  No same-day monthly capitation code (90960-90962) is being billed for the same patient

✔  Claim is being submitted within the payer's timely filing window

✅  Pre-Submission Audit Checklist — CPT 90937

✔  TWO or more separately timed, individually authored physician evaluation notes are present for this session — OR documentation of active mid-session management with prescription revision is clearly present

✔  Each evaluation note is time-stamped and reflects distinct clinical findings at each assessment point during the session

✔  The clinical basis for repeated physician evaluation is explicit in the record (hemodynamic instability, complication, access issue, electrolyte emergency, etc.)

✔  If prescription revision occurred, the original prescription, revised prescription, and clinical rationale are all documented

✔  ICD-10 coding reflects the specific clinical condition that necessitated intensified physician management during the session

✔  POS code is confirmed and matches the actual treatment setting

✔  Physician signature and authentication are present on ALL evaluation notes for this session

✔  No same-day monthly capitation code is being billed concurrently for this patient

✔  Appeal documentation is pre-prepared for payers known to routinely challenge 90937 claims — include all timed notes in initial submission

12 — Compliance Tips & Revenue Optimization Strategies

Compliance Tips

🛡️  Conduct Quarterly Coding Audits  — Sample 90935 and 90937 claims quarterly — review documentation against billed code, confirm evaluation count, verify ICD-10 linkage. Catching systematic errors internally is far less costly than correcting them after a payer audit.

🛡️  Train Physicians on Timed Note Entries  — A 90937 claim that fails on audit often fails because the second evaluation is not timed in the note. Physicians should understand that each return visit to the patient during a dialysis session needs its own time-stamped, authenticated entry.

🛡️  Monitor 90937-to-90935 Billing Ratio  — Track the ratio of 90937 to 90935 claims per physician per quarter. If any provider bills 90937 for nearly all sessions, that pattern warrants documentation review — it may indicate overcoding or insufficient documentation practices.

🛡️  Retain Records Minimum Seven Years  — CMS requires Medicare dialysis records to be retained for at least seven years from the date of service. State laws may require longer. Per-session notes, treatment logs, and physician evaluations must all be retained and accessible.

🛡️  Build Pre-Submission QA Into Workflow  — The most cost-effective compliance investment: review every 90937 claim before it is submitted. A 90937 claim that fails audit costs more to recover than the original payment — pre-submission QA prevents that scenario.

Revenue Optimization Strategies

📈  Eliminate Systematic Undercoding  — Practices that default to 90935 for all hemodialysis sessions — even when clinical records document multiple evaluations — lose recoverable revenue on every session where 90937 was warranted. Quarterly documentation review identifies undercoding patterns.

📈  Improve Per-Session Claim Release Time  — Per-session claims that age more than 14 days before submission are at timely filing risk and represent cash flow delay. Build physician note completion requirements that align with your billing team's submission window.

📈  Verify All Commercial Payer Contracts  — If your practice has not reviewed contracted rates for hemodialysis codes in the past two years, there is a meaningful chance you are being reimbursed below your contracted rates. Systematic underpayment review for 90935 and 90937 often uncovers immediate recovery opportunities.

📈  Implement Denial Trend Analytics  — Track denial reason codes for 90935 and 90937 by payer, by provider, and by denial type. Denial patterns drive systemic workflow corrections that compound into material annual revenue improvement.

📈  Leverage Technology for Documentation  — EHR templates specifically designed for hemodialysis physician evaluations — including time-stamp prompts, evaluation checklists, and prescription revision fields — reduce documentation gaps and improve per-session coding accuracy.

🏆  Why Nephrology Practices Choose MedCloudMD for Hemodialysis Billing

Hemodialysis billing combines per-session coding complexity, intensive documentation requirements, Medicare compliance obligations, and commercial payer variation into one of the most demanding billing environments in medicine. Our nephrology billing team at MedCloudMD is built specifically for this environment — not as a general billing company with a nephrology specialty, but as a revenue cycle organization whose core expertise is in dialysis and nephrology billing.

✔  Nephrology Billing Specialists — dedicated billers and coders who work exclusively in nephrology, including 90935/90937 per-session billing and the full ESRD code family

✔  Documentation QA on Every Claim — pre-submission review of evaluation count, note completeness, ICD-10 linkage, POS, and modifiers before any claim reaches the payer

✔  Denial Management — every denied hemodialysis claim is routed for appeal within our standard 5-business-day protocol; we track reason codes and fix root causes

✔  Medicare Compliance Monitoring — we track CMS Physician Fee Schedule updates, OIG audit priorities, and MAC-specific billing guidance and update your workflows accordingly

✔  Commercial Payer Authorization Support — prior authorization management for commercial payers requiring PA for hemodialysis services

✔  Revenue Cycle Optimization — quarterly coding audits, denial trend analytics, and revenue performance reporting specific to your dialysis billing volume

✔  Accounts Receivable Follow-Up — per-session claim aging tracked per patient; underpayments identified and followed up within your contractual appeal window

✔  Credentialing Support — ensure your providers are enrolled and credentialed with every payer in your revenue cycle before claims are submitted

Learn more: medcloudmd.com/specialties/nephrology-billing-services

14 — Frequently Asked Questions: CPT 90935 & 90937

Q1:  What is CPT Code 90935?

CPT 90935 is a per-session hemodialysis code that applies when a physician or qualified healthcare professional provides a single evaluation during a hemodialysis treatment. It covers the physician's clinical management of the patient during that individual dialysis session including assessment, orders, and documentation of patient response. It is billed once per session and is appropriate when one evaluation is clinically sufficient.

Q2:  What is CPT Code 90937?

CPT 90937 is a per-session hemodialysis code that applies when the patient's condition during the session requires multiple physician evaluations or active management that includes, or may include, a substantial revision of the dialysis prescription. It reflects a higher level of physician involvement during the treatment than 90935 and requires documentation that clearly supports more than a single evaluation during the session.

Q3:  What is the difference between CPT 90935 and 90937?

The difference is the number and intensity of physician evaluations during the hemodialysis session. CPT 90935 applies when the physician evaluates the patient once and that single evaluation is sufficient to manage the session. CPT 90937 applies when the patient requires multiple physician evaluations during the session because of complications, hemodynamic instability, or a need for prescription revision. Diagnosis severity alone does not determine which code to use; intra-session physician activity does.

Q4:  Does Medicare reimburse CPT 90935?

Yes. Medicare covers CPT 90935 under Part B as a physician service during hemodialysis. The reimbursement rate is based on the code's assigned RVUs, multiplied by the annual Medicare Conversion Factor, and adjusted by the Geographic Practice Cost Index for your location. Exact rates change annually with the Physician Fee Schedule — verify the current year's rate with CMS or your MAC.

Q5:  What documentation is required for these codes?

For CPT 90935: one complete, dated, timed, and physician-signed evaluation note documenting clinical assessment, patient response, and management decisions during the session. For CPT 90937: multiple individually timed and authored physician evaluation notes, OR documentation of active management that substantially revised the dialysis prescription, with all clinical reasoning explicitly captured. For both codes, ICD-10 diagnosis must be supported by the clinical record.

Q6:  Can these codes be billed with other dialysis services?

CPT 90935 and 90937 cannot be billed on the same day as the ESRD monthly capitation codes (90960, 90961, 90962) for the same patient. They represent different billing constructs — per-session versus monthly management — and billing both on the same date creates a conflict that results in denial. Verify modifier requirements and code combination restrictions with your specific payers before combining these codes with any other same-day service.

Q7:  What are the most common reasons dialysis claims are denied?

The most common denial reasons for CPT 90935 and 90937 include: billing 90937 with documentation supporting only one evaluation (upcoding); insufficient or missing physician evaluation notes; same-day conflict with monthly capitation codes; incorrect ICD-10 diagnosis not supporting medical necessity for acute hemodialysis; wrong place of service code; missing or incorrect modifiers; and timely filing violations. Most are preventable with pre-submission claim review.

Q8:  Are modifiers required for CPT 90935 or 90937?

Modifiers are not routinely required for 90935 or 90937 in most billing scenarios. However, modifier -25 may be appropriate if a separately identifiable evaluation and management service was performed on the same date as the hemodialysis service. Modifier -59 may apply when a distinct procedural service needs to be distinguished. Modifier requirements vary by payer — always verify your specific payer's modifier policies rather than assuming universal applicability.

Q9:  How can nephrology practices improve hemodialysis billing accuracy?

The most impactful improvements come from: requiring physician note completion before claim release, implementing per-session pre-submission documentation QA, conducting quarterly internal coding audits of 90935 and 90937 claims, training physicians on the documentation difference between the two codes, tracking denial reason codes by trend to identify workflow gaps, and reviewing commercial payer underpayments against contracted rates. Practices that implement these steps consistently report meaningfully cleaner claim rates and faster payment cycles.

Q10:  How does MedCloudMD support nephrology practices billing CPT 90935 and 90937?

Our nephrology billing team manages the complete 90935 and 90937 billing workflow: documentation review before coding, code selection verification, ICD-10 alignment, pre-submission claim scrubbing, electronic submission, payment posting, underpayment review, and denial management. We also provide quarterly coding audits and revenue analytics specific to your dialysis billing volume. If your practice is experiencing denials or reimbursement issues with these codes, a free billing assessment from our team is the fastest way to identify the root cause. Contact us at medcloudmd.com/contact-us.

📌  Key Takeaways

✔  CPT 90935 = single physician evaluation during the hemodialysis session; CPT 90937 = multiple evaluations or active management with possible prescription revision

✔  Both codes are per-session, not monthly — they are billed per treatment, not per month like ESRD MCP codes 90960-90962

✔  Code selection is driven by what the physician documented during the session — not by the severity of the underlying diagnosis

✔  CPT 90937 requires multiple individually timed, authenticated physician evaluation notes or explicit prescription revision documentation to withstand audit

✔  Do not bill 90935 or 90937 on the same day as monthly ESRD capitation codes for the same patient — this creates a payer conflict and denial

✔  Pre-submission documentation QA — confirming evaluation count, note completeness, ICD-10, and POS — is the most effective denial prevention tool for these codes

✔  90937 is one of the highest-scrutinized codes in dialysis billing; billing it without supporting documentation is an upcoding risk with compliance consequences

✔  Quarterly internal coding audits and per-session denial trend tracking are minimum compliance practices for any practice billing significant dialysis volume

⚖️  Disclaimer: This blog post is intended for general educational and informational purposes only and does not constitute legal, regulatory, compliance, financial, or professional medical coding advice. CPT codes 90935 and 90937, their documentation requirements, billing guidelines, and reimbursement policies are subject to annual updates by the American Medical Association (AMA) and the Centers for Medicare & Medicaid Services (CMS). Policies may also vary by payer, state, geographic location, facility type, and specific contractual or clinical circumstances. Healthcare providers, medical billers, practice administrators, and compliance officers should independently verify all current coding, documentation, billing, and payer-specific requirements with their compliance officer, a Certified Professional Coder (CPC), their Medicare Administrative Contractor (MAC), or the applicable regulatory or professional authority before making coding or billing decisions. MedCloudMD makes no representations regarding specific reimbursement amounts for CPT 90935 or 90937, as payment rates vary by payer, geographic location, annual CMS updates, and contracted terms. Clinical scenarios, examples, and billing scenarios described in this article are illustrative composites for educational purposes only; no patient-identifying information is used. This content reflects publicly available CMS and AMA coding guidance as understood at the time of publication in 2026 and should not be relied upon as a substitute for current, verified, payer-specific guidance or professional advice.