CPT code 28035 – Tarsal tunnel release

Key takeaways

CPT code 28035 describes release of the tarsal tunnel (posterior tibial nerve decompression) and carries a 90-day global surgery period.

The 2026 national, unadjusted Medicare rate for 28035 is about $545 non-facility and $344 facility, before GPCI adjustment.

Medicare and commercial payers handle bilateral 28035 claims differently, so confirm whether the payer wants modifier -50 or separate -RT and -LT lines.

ICD-10 codes G57.50, G57.51, and G57.52 are the primary diagnosis codes supporting medical necessity for 28035.

Pabau’s claims management tools support podiatric billing workflows, including modifier application and claim submission through the Claim.MD clearinghouse integration.

CPT code 28035: Official descriptor and procedure overview

CPT code 28035 is defined by the American Medical Association with the official descriptor: “Release, tarsal tunnel (posterior tibial nerve decompression).” It belongs to the Incision Procedures on the Foot and Toes section of the CPT code book, which spans codes 28001 through 28035.

The code captures the full surgical release of the flexor retinaculum at the medial ankle to decompress the posterior tibial nerve and its terminal branches. It is a unilateral code by default, so bilateral procedures need a modifier. The table below summarizes its key administrative attributes.

ICD-10 codes linked to CPT code 28035

Medical necessity for CPT code 28035 rests on an ICD-10-CM code for tarsal tunnel syndrome or a clinically equivalent nerve entrapment. Payers will deny the claim if the submitted diagnosis does not appear on the payer’s local coverage determination (LCD) for peripheral nerve decompression procedures.

Confirm diagnosis codes against the applicable Medicare LCD or commercial payer policy before submission. The AAPC Codify CPT lookup includes ICD-10 crosswalk data that can help verify which diagnosis codes each payer accepts alongside 28035.

Medicare reimbursement for CPT code 28035 in 2026

The 2026 Medicare reimbursement rate for CPT code 28035 varies by location. CMS applies a Geographic Practice Cost Index (GPCI) adjustment to the national base rates. Use the CMS Physician Fee Schedule lookup tool to retrieve the exact non-facility and facility rates for your MAC jurisdiction.

The figures below are national, unadjusted 2026 amounts, before the GPCI adjustment for your locality. Verify your local rate before quoting patients or appealing underpayments.

The FastRVU 2026 lookup tool breaks out work, practice expense, and malpractice RVUs alongside the conversion factor. That helps when you validate commercial contracts built on an RVU-based fee schedule.

The surgeon’s work RVU is identical in both settings. Practice expense and malpractice RVUs alone account for the roughly $200 difference between the two rates.

Pabau, the practice management platform we build, sends 28035 claims through its Claim.MD clearinghouse connection. The ERA remittance data that comes back can be reconciled against these expected rates.

Modifiers for CPT code 28035

Modifier selection for CPT code 28035 depends on the payer, the number of sides operated, and whether the case involved unusual complexity. The table below maps each common modifier to its use case.

Bilateral billing decision rule: Medicare Administrative Contractors generally prefer two separate line items rather than a single line with -50. Each line, 28035-RT and 28035-LT, is paid at 100% of the allowed amount. Many commercial payers accept -50 on a single line at 150%. Confirm the payer-specific rule before submission. Submitting -50 to a Medicare MAC that expects separate lines is a common and easily avoidable denial trigger.

Global surgery period for CPT 28035

CPT code 28035 carries a 90-day global surgery period under the Medicare Physician Fee Schedule. The surgical fee bundles the preoperative visit on the day before or day of surgery and the intraoperative service. It also covers routine postoperative care for 90 days after the procedure.

These services are bundled into the global period and cannot be billed separately without a modifier:

• Routine postoperative office visits related to the surgical procedure
• Suture and staple removal
• Wound checks and dressing changes directly related to the tarsal tunnel release
• Postoperative pain management with standard analgesics

These services may be billed separately during the global period with the right modifier:

• Treatment of a complication requiring a return to the operating room: Use modifier -78
• An unrelated E/M service for a condition not related to the surgery: Use modifier -24
• A new surgical procedure on the same foot that is unrelated to the tarsal tunnel release: Use modifier -79
• Nerve conduction studies ordered postoperatively to evaluate a new or worsening neurological symptom unrelated to the tarsal tunnel release

CPT codes commonly confused with 28035

Four codes sit close enough to 28035 to be picked by mistake for a nerve or fascia release in the foot or ankle. The closest is 28008, which releases fascia without decompressing the nerve. A wrong code here triggers a denial, and a repeated one can draw an audit.

Documentation requirements for a clean 28035 claim

Payers require specific clinical elements in the operative note and the prior authorization request before they process a CPT code 28035 claim. Your medical billing record has to show that surgery was medically necessary and that conservative management failed. The intraoperative findings also have to match the stated diagnosis.

The operative note must include all of the following:

• Patient position, anesthesia type, and tourniquet application site
• Incision location: Typically a curvilinear incision posterior to the medial malleolus extending to the abductor hallucis muscle
• Identification of the posterior tibial nerve and its terminal branches (medial plantar, lateral plantar, medial calcaneal)
• Method and extent of flexor retinaculum division
• Description of nerve condition: Adhesions, fibrosis, compression from varicosities or space-occupying lesions
• Wound irrigation and layered closure technique
• Laterality clearly stated: Right, left, or bilateral (and which side completed first if bilateral)

Pre-surgical documentation submitted with the authorization request (when required) must demonstrate:

• Duration of conservative treatment: Typically 3-6 months minimum, though thresholds vary by payer
• Nerve conduction study (NCS) or electromyography (EMG) results confirming posterior tibial nerve dysfunction
• Record of tried and failed conservative measures: Orthotics, physical therapy, corticosteroid injections, anti-inflammatory medications
• Physician attestation that surgery is the clinically appropriate next step

The nerve conduction study itself is billed separately, under 95907 to 95913 depending on how many nerves were studied.

Prior authorization requirements for CPT 28035

Prior authorization status for CPT code 28035 varies significantly by payer. Medicare Part B does not require prior authorization for most outpatient surgical procedures, but Medicare Advantage plans and commercial insurers frequently do. Always verify with the specific plan before scheduling surgery.

Confirm billing compliance requirements for each payer at the time of booking to avoid scheduling surgery without an approved authorization. A claim submitted without a required prior auth is a denial that cannot be corrected retroactively in most plans.

Common 28035 denials and how to prevent them

CPT code 28035 denials cluster around five root causes. The denial management workflow for podiatric surgery codes is more effective when practices track denial reason codes systematically rather than addressing each claim in isolation. The table below maps the most frequent denial categories to the relevant CARC codes and the corrective action.

Tracking medical billing denial codes at the code level shows where a denial pattern starts. It may be coder-driven (wrong modifier), documentation-driven (missing conservative-care records), or authorization-driven (no prior auth). Pabau routes 28035 claims through its podiatry claims management workflow and shows ERA denial reason codes in the claims dashboard. Billing staff see CARC data without logging into the payer portal.

How Pabau supports podiatric billing workflows for CPT 28035

Podiatric surgery practices billing 28035 often work across three systems. Conservative-care notes sit in the EHR, authorizations in a payer portal, and claims in a separate billing tool. Because modifier rules change by payer, each claim gets checked by hand.

Pabau keeps the clinical record, the billing workflow, and claim submission in one platform. Its Claim.MD clearinghouse connection submits 837P claims to over 4,000 US payers and returns eligibility results. The 835 remittance files land in the billing dashboard, beside the original claim.

The outcome is a 28035 claim whose modifiers, diagnosis, and authorization match the note it came from. Before releasing a surgical code, the clean claim checklist covers the last pre-submission checks.

Manage podiatry billing from one platform

Pabau supports CPT code submission, modifier application, and ERA reconciliation for podiatric surgery practices. See how the claims workflow handles 28035 and adjacent foot surgery codes.

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Conclusion

The work that decides whether a 28035 claim pays happens before the incision. Confirm the payer’s bilateral rule, secure the authorization, and make sure months of conservative care are on record.

With that done, the operative note only has to confirm the side and the extent of the retinaculum release. Without it, the claim lands in the appeals queue, where the missing record still has to be found.

Pabau keeps conservative-care notes, the operative record, and the claim in one system, so the authorization file and the claim tell the same story. Book a demo to see a podiatric surgery claim go from operative note to submission.

Continue your research

Need to understand how clearinghouse submission works for surgical codes? Claim.MD clearinghouse guide explains how 837P claims are validated and routed to payers.

Seeing recurring claim rejections across multiple CPT codes? Revenue cycle management overview covers the end-to-end workflow from claim creation to payment posting.

Want to benchmark your denial rate against typical podiatric billing thresholds? Best medical billing software for US practices outlines what to look for in a billing platform that handles surgical code complexity.

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