HCPCS code A4637 – Replacement Mobility Aid Tip

Key takeaways

HCPCS code A4637 covers a single replacement tip for a cane, crutch, or walker, billed per tip rather than per episode of care.

Medicare Part B pays for A4637 only as a replacement tip on equipment the beneficiary already owns, once the old tip is worn or damaged.

Base cane and crutch codes already include tips, so A4637 is billed for replacements after delivery, never alongside a new device.

A4637 is billed with the standard supply modifiers, usually NU, or RR where the payer allows it. KX applies only if a current policy for the item says so.

Most A4637 denials trace back to base equipment not on file, wrong unit counts, frequency limits, or a lapsed DMEPOS enrollment.

What is HCPCS code A4637 and what does it cover?

HCPCS code A4637 is an active Level II code that describes a replacement tip for a cane, crutch, or walker, each. It sits in the A-code range for medical and surgical supplies, among the replacement parts codes A4630-A4640. The “each” in the descriptor means one unit equals one tip, so two tips replaced on the same date are billed as two units.

The code applies to three equipment types: canes (standard and quad), crutches (underarm and forearm), and walkers (standard and wheeled). Each tip replaced is a separate unit. Rollator wheels, brake pads, and glide caps are not tips and are not billed under A4637.

• Standard cane tips: rubber ferrules on single-point or offset canes
• Quad cane tips: each of the four tips counts as one unit
• Underarm crutch tips: the rubber end tip at the base of the crutch
• Forearm (Lofstrand) crutch tips: same billing logic as underarm crutches
• Standard walker tips: rubber end caps on non-wheeled walkers
• Wheeled walker tips: tip-bearing legs only; wheels and brakes use separate codes

Official descriptor and classification for HCPCS code A4637

The full official descriptor, as maintained by the Centers for Medicare and Medicaid Services (CMS), is: Replacement, tip, cane, crutch, walker, each. The table below captures the classification details coders need when verifying the code or entering it in a billing system.

Medicare coverage criteria for A4637

Medicare Part B covers A4637 under the DME benefit when all three conditions below are met.

1. The beneficiary already owns covered ambulatory equipment. The supplier must already have the base E-code on file. That means a qualifying cane (E0100, E0105), crutch (E0110, E0112, E0114), or walker (E0130, E0135, E0141, E0143).
2. The tip is worn or damaged. A replacement is needed when the existing tip poses a fall risk or no longer grips safely. The supplier file must record the worn or damaged condition.
3. The base item meets its own coverage policy. Canes and crutches fall under the DME MAC Canes and Crutches LCD (L33733) and its policy article A52459. Walkers fall under the Walkers LCD (L33791) and policy article A52503. That article says A4636, A4637, and E0159 are only used for replacement items on covered, beneficiary-owned walkers.

Medicaid coverage varies by state. Minnesota DHS, for example, maintains its own DMEPOS policy for ambulatory assist equipment replacement supplies. Commercial payers may follow Medicare rules or apply their own frequency and necessity standards. Verify each payer’s policy before billing.

2026 Medicare fee schedule and payment allowance for HCPCS code A4637

The 2026 Medicare allowance for HCPCS code A4637 is a per-unit purchase amount set in the DMEPOS fee schedule, and it varies by state. Pull the amount for your state from the DMEPOS fee schedule file on the CMS DMEPOS fee schedule page. CMS updates the file during the year, so check the current release before you load the rate.

How to bill HCPCS code A4637: modifiers and claim requirements

Billing A4637 correctly takes the right modifier, the right unit count, and a clean claim submission backed by the supplier file. The table below shows which modifiers apply and when.

File A4637 on a CMS-1500 form (or 837P electronic transaction). Use place of service 12 (home) for most DME supply deliveries. The supplier must be enrolled in Medicare as a DMEPOS supplier to bill the code to Medicare.

The first tips come with the device: The base codes for canes and crutches already include tips. E0100 and E0105 cover canes with tips, and E0110, E0112, and E0114 cover crutches complete with tips. That means A4637 is never billed alongside a new cane or crutch on its delivery date. It is for replacement tips after delivery only. The Walkers policy article (A52503) applies the same rule to walkers and bars billing A4637 at the same time as the walker base code.

A4637 vs related HCPCS codes: how to choose

A4637 is the only HCPCS Level II code for replacement tips on canes, crutches, and walkers. Coders sometimes reach for nearby codes when the part doesn’t map cleanly.

Crutch pads and handgrips: Underarm pads and handgrips are not tips. A worn underarm pad is billed as A4635 (underarm pad, crutch, replacement, each). A worn handgrip on a cane, crutch, or walker is A4636 (replacement, handgrip, cane, crutch, or walker, each). When a supplier replaces several crutch parts on one visit, each part goes on its own line under its own code.

The chart below maps each replaceable part to its code, and shows why the first set of tips never takes A4637.

Documentation requirements to support an A4637 claim

Medicare and commercial payers can audit A4637 claims years after payment. The supplier file must be able to produce each of the following on request. Strong medical billing compliance habits protect against post-payment recoupment.

• Diagnosis supporting ambulatory aid use: A physician or treating practitioner order or note documenting why the patient needs the cane, crutch, or walker. Typical reasons are lower-extremity weakness, fracture, or post-surgical ambulation.
• Evidence of existing qualifying equipment: The delivery receipt or rental agreement showing the base E-code item was provided to this beneficiary. A4637 is a replacement supply, so it cannot be billed without the primary equipment on file.
• Documentation of wear or damage: A supplier note, technician assessment, or patient statement confirming the existing tip is worn, cracked, or missing. Record it on the service ticket in writing or with a photo.
• Signed delivery receipt for the replacement tip: The beneficiary or an authorized representative must sign for the A4637 item. Unsigned receipts are a recoupment trigger.
• Supplier DMEPOS enrollment confirmation: The billing supplier must hold an active Medicare DMEPOS supplier number. A claim under an unenrolled supplier number fails regardless of clinical need.
• Support for any policy-specific modifier: Some payer policies require KX or a similar attestation modifier for an item. Where one does, keep the evidence for it in the supplier file.

Common denial reasons for A4637 claims and how to avoid them

A4637 carries a low allowable, but it is denied for the same reasons as higher-cost DME supply codes. The table below lists the patterns to check before a claim goes out. Matching each one to its CARC denial codes helps coders resolve and resubmit faster, and a set denial management workflow keeps the fixes consistent.

How Pabau helps you track A4637 claims and denials

Low-value replacement claims like A4637 often end up tracked in a spreadsheet, apart from the record of what each patient already owns. When a tip claim comes back denied, someone has to rebuild the story from both.

Pabau, the practice management platform we build, keeps the patient record, invoices, and claims in one system. Its denial-tracking claims management helps teams follow each claim’s status and see denials as they arrive.

Your team can see which tip claims are open and which were denied without switching tools. That makes it quicker to correct a unit count or a missing base-equipment record and resubmit.

Track supply claims and denials in one place

Pabau helps your team track claim status and denials for supply codes like A4637, with the patient record and invoices in the same system.

Book a demo

Conclusion

A4637 pays little per unit, so a denied tip claim can cost more to rework than the tip is worth. The fix belongs before submission. Confirm the beneficiary owns the base item, count tips against the device, and check the payer’s frequency limit.

Treat KX, RA, and similar modifiers as payer-specific until a current policy for the item asks for them. NU covers a purchased tip in most cases, and a modifier no policy requires only invites questions.

Still tracking supply claims across separate tools? Book a demo to see how Pabau keeps claim status and denials next to the patient record.

Continue your research

Need to understand how claim denials are categorized? Denial codes in medical billing explains the CARC and RARC code structure used on remittance advice for DME and other claim types.

Billing the base walker too? HCPCS code E0135 covers the folding pickup walker that replacement tips are most often fitted to.

Looking to reduce overall claim rejection rates? Clean claim submission covers the eligibility, modifier, and documentation checks that prevent rejections before they reach the payer.

Want a broader view of DME billing compliance? Medical billing compliance outlines the audit triggers and documentation standards that apply across Medicare Part B supply codes.

Frequently asked questions