HCPCS Code A4580: Cast supplies (plaster) billing guide

Key Takeaways

HCPCS Code A4580 describes cast supplies (e.g., plaster), a Level II HCPCS A-code for medical and surgical supplies.

CMS declared A4580 (along with A4570 and A4590) invalid for Medicare use effective July 1, 2001. Medicare and Medicare Advantage plans require the temporary Q-code crosswalk (Q4001-Q4051) instead, selected by cast material, patient age, and cast type.

A4580 may still be accepted by some commercial payers and a small number of state Medicaid programs (North Carolina Medicaid is a confirmed example), so always verify the specific payer’s preferred code before submitting.

Pabau’s claims management software helps orthopedic and DME billing teams attach the correct supply code, whether that is A4580 or a Q4001-Q4051 crosswalk code, to treatment records at the point of care.

HCPCS Code A4580 covers cast supplies made of plaster, but it is not payable under Medicare. The Centers for Medicare & Medicaid Services (CMS) invalidated A4580 for Medicare use in 2001, yet it still turns up in billing references and software dropdowns as though it belongs on a Medicare DME claim.

Practice management software like Pabau can route the correct supply code, A4580 or the matching Q-code, to the right payer through its claims management software, linking it to the clinical record at the point of care.

HCPCS Code A4580: Definition and code details

HCPCS Code A4580 is the Level II supply code for cast supplies made of plaster. Billers searching for the formal long description will find it listed as Cast supplies (e.g., plaster) in the official CMS HCPCS code file. It sits in the A-codes section, which covers medical and surgical supplies.

The code is still listed in the HCPCS file, but CMS removed it from Medicare use in 2001. Being listed is not the same as being an active, Medicare-payable code.

The table below captures every attribute a biller needs before submitting a claim involving plaster cast supplies:

A4580 is not interchangeable with its sibling code A4590, which covers special casting material such as fiberglass. Plaster-based supplies are the specific scope of A4580, so the choice between the two codes starts at the supply room, not the billing desk.

Both codes share the same Medicare status. CMS invalidated A4570, A4580, and A4590 together, effective July 1, 2001, and replaced all three with the temporary Q4001-Q4051 code series.

Clinical use cases for HCPCS Code A4580

Plaster cast supplies are used across several clinical scenarios, all involving the need to immobilize a body part while the material sets. Three situations account for the majority of plaster cast supply claims:

• Fracture immobilization: the most common indication. When a physician applies a plaster cast to manage a closed or displaced fracture, the supply materials are billed separately from the appropriate CPT cast application code in the 29000 series.
• Post-operative casting: orthopedic surgeons often immobilize a surgical site with a plaster cast in the immediate recovery period. The supply billing logic is the same as fracture casting, even though the triggering event was surgery rather than trauma.
• Joint stabilization: certain inflammatory joint conditions and soft tissue injuries require temporary plaster immobilization outside of fracture or surgical contexts, sometimes alongside supportive devices such as L2820. Medical necessity documentation becomes especially important here, since payers scrutinize non-fracture casting claims more closely.

In all three cases, the supply code covers the physical materials only. The professional work of applying the cast is captured by the relevant CPT code, such as 29075 (application of short arm cast, elbow to finger) or 29065 (application of long arm cast, shoulder to hand).

Billing both the CPT application code and a supply code for the same encounter is correct. Bundling them into a single line item is not, a mistake sports medicine practices run into often given high fracture-casting volume.

Whether that supply code is A4580 or a Q4001-Q4051 crosswalk code depends entirely on the payer, covered in the billing guidelines below.

Practices managing post-surgical orthopedic care benefit from having supply usage tied directly to the patient record. Physical therapy practices using integrated practice management can associate supply codes with appointment records at the point of care, reducing the chance of a supply claim being overlooked when the clinical record is finalized.

How to bill HCPCS Code A4580: Billing guidelines by payer type

Most claim errors involving plaster cast supplies come from one source: treating A4580 as a universal code without checking whether the specific payer still accepts it. The steps below start with that check, then cover diagnosis pairing and modifiers.

1. Identify the payer type first. This single step determines whether A4580 is billable at all for the claim in front of you.
2. For Medicare and Medicare Advantage: do not bill A4580. CMS declared it invalid for Medicare use effective July 1, 2001 (CMS Program Memorandum AB-01-60), and it has remained non-payable since. Select the matching code from the Q4001-Q4051 crosswalk instead, based on cast material (plaster vs. fiberglass), patient age (adult 11+ vs. pediatric 0-10), and cast type (body, shoulder, long arm, short arm, hip spica, long leg, short leg, and so on). See the crosswalk table below. Submitting A4580 to a DME MAC or Medicare Advantage plan will be rejected as invalid.
3. For commercial payers and Medicaid: verify the payer’s preferred code before submitting. Many commercial plans still accept A4580 for plaster cast supplies, though a growing number crosswalk to the Q-codes to stay aligned with Medicare. State Medicaid programs vary: some states, North Carolina among them, explicitly permit A4570/A4580/A4590 billing for cast and splint supplies, while others require the Q4001-Q4051 series. Check the specific state Medicaid billing manual or provider handbook rather than assuming Medicare’s rules, or another state’s rules, apply.
4. Pair the supply code with the CPT cast application code. Regardless of whether the supply is billed as A4580/A4590 or a Q-code, it travels alongside the relevant CPT code (29000-series) on the same date of service. The CPT code captures the professional work. The supply code captures the materials. Both are billable.
5. Attach a supporting ICD-10 diagnosis code. Medical necessity is established through the accompanying diagnosis. Fracture S-codes are the most common pairings. See the ICD-10 section below for a reference table.
6. Confirm current modifier requirements with the specific payer. RT and LT (laterality) are commonly requested. Don’t assume any Medicare DME-era modifier rules tied to A4580 still apply, since A4580 was never a Medicare-payable code in the first place. See the modifiers section below.

Tracking which patients have received cast supplies, and confirming which code and payer combination applies, is where structured documentation workflows pay off. When the clinical record captures supply details and payer type at the time of application, the billing team has the evidence it needs without chasing the clinical team after the fact.

Medicare reimbursement for cast supplies: the Q4001-Q4051 fee schedule

CMS declared HCPCS codes A4570, A4580, and A4590 invalid for Medicare use effective July 1, 2001, per Program Memorandum AB-01-60, and replaced them with 51 temporary Q-codes (Q4001-Q4051) covering casts, splints, and casting/splinting supplies by material, patient age, and cast or splint type.

Current payer reimbursement policy confirms this remains the rule. 2026 UnitedHealthcare Medicare Advantage, commercial, and Medicaid supply reimbursement policies each state explicitly that Medicare and Medicare Advantage do not reimburse A4570, A4580, or A4590, and direct billers to the Q4001-Q4051 crosswalk instead.

CMS sets allowable reimbursement amounts for the Q4001-Q4051 series through the annual DMEPOS fee schedule, the same mechanism used for other durable medical equipment supply codes. Because specific dollar figures change with each update cycle and vary by fee schedule area, this guide does not publish a static rate.

Always verify current allowable amounts directly through the CMS fee schedule lookup tool, selecting the DMEPOS fee schedule and the correct Q-code for the cast type, material, and patient age billed. The lookup tool is free, updated annually, and reflects the most current contracted rates.

Key factors that affect the allowable rate for a Q4001-Q4051 claim:

• Fee schedule area: DMEPOS rates can vary by locality and by DME MAC jurisdiction. Confirm the current amount for the beneficiary’s fee schedule area rather than assuming a single national rate.
• Not part of competitive bidding: unlike higher-cost DME categories (glucose monitors, wheelchairs, ostomy and urological supplies), cast and splint supply codes are not part of the DMEPOS Competitive Bidding Program, so the standard published fee schedule applies rather than a bid rate.
• Medicaid and commercial payers: state Medicaid programs set their own rates independently of Medicare, and some, unlike Medicare, still recognize A4580/A4590 rather than the Q-codes. Commercial payer contracts may reference the Medicare fee schedule at a percentage or set rates independently. Verify each payer’s contracted rate, and preferred code, before assuming Medicare’s Q-code rules apply.

ICD-10 diagnosis codes commonly paired with HCPCS Code A4580

Every claim for plaster cast supplies, whether billed as A4580 or the matching Q-code, requires a supporting ICD-10-CM diagnosis code that establishes medical necessity. Fracture codes (S-codes) from ICD-10-CM are the most common pairings. The table below covers the most frequently submitted diagnosis codes, organized by anatomical region.

Use the full, specific ICD-10-CM code including laterality (right, left, unspecified) and encounter type (initial, subsequent, sequela). An unspecified laterality code where a specific one is available is a common reason for payer scrutiny during audits. Fracture codes such as S52.532N show how granular this specificity gets in practice.

Applicable modifiers for A4580 and its Medicare Q-code crosswalk

Modifier requirements differ depending on whether the claim is billed as A4580 (accepted by some commercial payers and select state Medicaid programs) or as the matching Q4001-Q4051 code (required for Medicare and Medicare Advantage). The table below covers the modifiers most commonly encountered.

Don’t carry over Medicare DME modifier habits from other supply categories onto A4580 or its Q-code crosswalk without checking the current billing article first.

A4580 was never a Medicare-payable code, so any claim, workflow, or system default that treats it as one, including automatic KX logic built around it, is working from an incorrect premise and should be corrected at the source.

Practices using HIPAA-compliant documentation workflows that capture physician orders and payer type digitally at the point of care are better positioned to confirm the correct code and modifier combination before submission.

Medicare and payer coverage for cast supplies billed with A4580

Coverage for plaster cast supplies depends entirely on which payer is billed and which code that payer expects. Always confirm the specific payer’s current policy before submitting, since the same clinical supply can require different codes depending on the plan.

Coverage considerations by payer type:

• Medicare Part B (including Medicare Advantage): A4580 is not payable. CMS declared it invalid for Medicare use effective July 1, 2001. Cast supply claims must use the matching Q4001-Q4051 crosswalk code instead. Two DME MAC contractors administer Medicare DMEPOS claims: Noridian Healthcare Solutions (Jurisdictions A and D) and CGS Administrators (Jurisdictions B and C). Submitting A4580 to either contractor, or to a Medicare Advantage plan, will be denied as an invalid code.
• Medicaid: coverage and preferred code vary significantly by state. Most states have followed CMS and require the Q4001-Q4051 series, but some have not: North Carolina Medicaid, for example, explicitly allows A4570, A4580, and A4590 to be billed for cast and splint supplies. Verify the specific state’s Medicaid billing manual and DMEPOS fee schedule before billing either code family.
• Commercial payers: most commercial plans cover plaster cast supplies when medically necessary, but whether they expect A4580 or the Q-code crosswalk depends on the individual payer’s reimbursement policy. Contracted rates also differ from Medicare. Verify the member’s benefit, preferred code, and any prior authorization requirements before providing supplies.
• Workers’ compensation: typically covered when the casting is directly related to a workplace injury. Workers’ comp payers generally use state fee schedules, which may reference Medicare DMEPOS rates, including the Q4001-Q4051 series, at a specified percentage.

For the authoritative source on the Medicare change itself, see CMS Program Memorandum AB-01-60, which invalidated A4570, A4580, and A4590 for Medicare use and introduced the Q4001-Q4051 series. For coding notes and payer coverage indicators, the AAPC HCPCS code reference aggregates coverage data from multiple payer sources and is updated frequently.

Manage HCPCS billing codes within your clinical workflow

Pabau helps DME suppliers and orthopedic practices route cast supply codes, A4580 or the correct Q4001-Q4051 crosswalk code, to the right payer with the documentation your billing team needs before submission.

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Related codes and crosswalk: A4580, A4590, and the Medicare Q-codes

The most common coding error involving A4580 is treating it as a Medicare-payable code. The crosswalk below covers A4580 and A4590 alongside the Q4001-Q4051 codes most frequently required in their place for Medicare and Medicare Advantage claims:

The A4580 vs A4590 decision, and the plaster-vs-fiberglass branch of the Q-code crosswalk, both start with the physical supply used. Plaster rolls and plaster splinting material map to A4580 or the “plaster” Q-code. Fiberglass rolls and synthetic thermoplastic casting systems map to A4590 or the “fiberglass” Q-code.

Getting the material wrong is an upcoding or underpayment risk in either code family, and it creates audit exposure regardless of which system is billed.

Pediatric equivalents (patients under 11) exist throughout the Q-code series, for example Q4007/Q4008 for long arm casts and Q4011/Q4012 for short arm casts, alongside separate code blocks for shoulder casts, gauntlet casts, splints, hip spicas, and long/short leg casts. Related supply items, such as A4452, follow similar payer-specific billing logic and should be verified individually.

Verify the exact code against the current CMS HCPCS file or the AAPC HCPCS code range reference before submission. A body-region mismatch is as costly a denial reason as a material mismatch. The CPT application code billed alongside it, such as 29515, should also be checked against the payer fee schedule.

Documentation best practices to avoid claim denials for cast supply billing

Denial-prevention documentation is where cast supply claims most often lose reimbursement after the fact, whether the claim was billed as A4580 or a Q-code. Payer audits for cast supplies examine four documentation elements specifically.

• Physician order: a signed, dated order from the treating physician documenting the need for cast supplies. The order must precede the supply delivery, not follow it. Post-dated orders are a common audit finding and a reason for recoupment.
• Written statement of medical necessity (WSMN): required by some payers for cast supply claims. The WSMN should reference the specific diagnosis, the type of cast applied, and the clinical reason immobilization is required. A generic order (“apply cast”) without diagnosis context does not satisfy this requirement.
• Clinical documentation supporting the diagnosis: the ICD-10-CM code submitted must be supported by the clinical record. Radiology reports confirming fracture, operative notes for post-surgical casting, or examination findings for non-fracture immobilization all satisfy this requirement when they are present in the record at the time of claim submission.
• Supply delivery confirmation: practices billing cast supplies directly, or the DME suppliers involved, should document that the supplies were actually used or delivered. This can be a delivery receipt, a signed beneficiary receipt, or a clinical note documenting supply use during an office visit.

Practices that digitize their documentation workflows reduce the risk of any of these four elements being missing at submission. Digital forms that capture physician orders and consent at the point of care create an audit-ready record from the start of the encounter.

Common denial reasons for cast supply claims, and how to prevent them:

Maintaining a denial log specific to cast supply claims and reviewing it monthly reveals patterns. If Medicare claims billed with A4580 instead of the correct Q-code account for a meaningful share of rejections, that is a coding-logic problem to fix at the source, not a documentation problem.

Inventory management software that logs which supply type (plaster vs fiberglass) and payer was used per encounter also helps eliminate material and code-family mismatches. The supply record creates an automatic audit trail.

Conclusion

HCPCS Code A4580 is a straightforward supply code once one fact is settled first: it is not payable to Medicare or Medicare Advantage, and has not been since July 1, 2001. Medicare claims need the matching Q4001-Q4051 crosswalk code, selected by material, patient age, and cast type. A4580 itself is reserved for the commercial payers and select state Medicaid programs that still accept it directly.

Beyond that payer check, the rest of the claim setup is familiar: plaster materials confirmed in the record, the correct ICD-10 fracture code attached, the right modifiers for the payer in question, and the supply code billed separately from the CPT casting procedure. Where practices lose money on cast supply billing is almost always this payer-and-code mismatch, not a documentation shortfall.

Pabau connects supply code documentation to the clinical record at the point of care, so billing teams can route A4580 or the correct Q4001-Q4051 crosswalk code with confidence. To see how Pabau handles HCPCS billing workflows in practice, book a demo with the team.

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