HCPCS code A4928 – Surgical mask, per 20

Key takeaways

HCPCS code A4928 is the Level II code for surgical mask, per 20, so one unit equals one pack of 20 masks.

CMS assigns A4928 type of service L (ESRD supplies) and Part B pricing indicator 00, meaning Part B does not price it separately.

The CY 2026 ESRD PPS consolidated billing list names A4928 as a DME ESRD supply that is not payable to DME suppliers.

N95 respirators, cloth masks and face shields fall outside the A4928 descriptor.

Most A4928 denials trace back to per-mask unit counts, a bundled setting, or a plan that excludes masks.

HCPCS code A4928: Surgical mask, per 20

HCPCS code A4928 is the Level II code for a surgical mask, reported per pack of 20. It belongs to Healthcare Common Procedure Coding System (HCPCS) Level II, the alphanumeric code set the Centers for Medicare & Medicaid Services (CMS) maintains. Level II covers supplies, equipment, and services that CPT does not describe.

A codes are one section of the HCPCS Level II codes, running from A0000 to A9999. They cover transportation services, medical and surgical supplies, and administrative items. Medical and surgical supplies sit in the A4000 to A8999 range, and A4928 falls inside it.

CMS gives A4928 type of service L, the indicator for end-stage renal disease (ESRD) supplies. That places the code in the dialysis supply family alongside gloves, tourniquets, and other items used at the chair.

CMS updates the HCPCS Level II file every quarter, so check the current release before you rely on any status above.

What A4928 covers and what it excludes

A4928 covers disposable surgical masks, the loose-fitting fluid-resistant masks worn during dialysis and other clinical procedures. The descriptor names no sterility status, brand, or ear-loop style, so any surgical mask fits it.

Included in A4928

• Disposable surgical masks with ear loops or ties
• Fluid-resistant procedure masks used by staff or patients during dialysis
• Surgical masks supplied in packs, reported in units of 20

Outside the A4928 descriptor

• N95 and other fitted respirators — a respirator is a different product from a surgical mask, so it does not match the descriptor
• Cloth or reusable face masks — these are not surgical masks
• Face shields and goggles — eye and face protection is a separate item
• Gloves — non-sterile gloves are A4927 and sterile gloves are A4930

If a payer covers respirators or other protective equipment, its own policy names the code to use. Never stretch A4928 to cover a product the descriptor does not describe.

How to report units for A4928

One unit of A4928 equals one pack of 20 masks. A pack of 40 masks is reported as 2 units, and a box of 100 masks is reported as 5 units.

The most common unit mistake is counting individual masks. Reporting 20 units for one pack overstates the quantity twentyfold and invites a denial or an audit.

The descriptor defines no partial unit. If you dispense fewer than 20 masks, check the payer’s rounding rule before you report the line.

A4928 and ESRD dialysis billing

A4928 sits on the CMS list of supplies tied to the ESRD prospective payment system (PPS). The ESRD PPS pays dialysis facilities a bundled rate per treatment that covers the supplies used to deliver it.

On the CY 2026 ESRD PPS consolidated billing list, A4928 appears under DME ESRD supply codes that are not payable to DME suppliers. A supplier claim for masks given to a dialysis patient therefore hits a consolidated billing edit and is not paid separately.

For dialysis facilities, the masks are a cost inside the bundled rate. Do not expect a separate payment for them on the facility claim.

The same CMS list includes A4929 for dialysis tourniquets and A4930 for sterile gloves, alongside A4927 for non-sterile gloves. Treat the whole group the same way when you set up ESRD supply billing rules.

Medicare coverage and pricing for A4928

Medicare gives A4928 coverage code D, which means special coverage instructions apply. Those instructions come from CMS manuals and your Medicare Administrative Contractor (MAC), so read your contractor’s guidance before you bill the code.

The Part B pricing indicator for A4928 is 00. CMS uses that value for services not separately priced by Part B, such as bundled or non-covered items.

In practice, Medicare Part B does not set a separate payment amount for a pack of surgical masks. In an office visit, masks count as practice overhead and are not billed as their own line.

Medicare Advantage, Medicaid, and commercial plans set their own supply rules. Some list A4928 on a supply fee schedule, while others exclude masks entirely. Check the plan’s current fee schedule and coverage policy before you dispense masks you intend to bill.

Put the unit rule and the three payer routes side by side, and each A4928 line has one likely outcome.

Related HCPCS codes

A4928 is one of several ESRD supply codes that billers mix up. The table below lists its closest neighbors on the CMS consolidated billing list.

Use A4913 only when no specific code fits. A surgical mask always has one, so it belongs on A4928. Gloves have their own codes too, starting with A4927 for non-sterile gloves.

Documentation for an A4928 claim

When a payer covers A4928, the record has to support every claim line. Keep these details in the patient record:

• Product — a surgical mask, not a respirator or cloth mask
• Quantity — the number of masks dispensed and the matching unit count
• Date of service — the date the masks were supplied
• Diagnosis — the ICD-10-CM code that supports the supply under the payer’s policy
• Setting and patient status — whether the patient is on dialysis, since that decides whether the ESRD bundle applies
• Payer authorization — any approval number, if the plan requires one

Store supply invoices and any payer policy you relied on with the claim file. Our guide to medical billing compliance covers record keeping for supply billing in more depth.

Common A4928 denial reasons and how to fix them

A4928 denials usually come from the code’s pricing status or its unit, rather than from the mask itself. The table maps each pattern to a fix.

A steady denial management process traces each denial back to one of these causes. Fix the setup that produced it rather than resubmitting the same line.

Keep supply billing on the patient record with Pabau

Supply lines such as A4928 go wrong when the note, the stock count, and the claim sit in different systems. A biller then reconstructs the quantity from memory or bills a code the payer bundles.

Pabau, the practice management platform we build, keeps the treatment note, inventory, and invoice on the same patient record. Its claims management software lets your team raise, submit, track, and reconcile claims in one view.

Your team can then compare each supply line with the record before it leaves the practice. If a payer asks questions later, the trail is already in one place.

Keep supply claims tied to the patient record

Pabau keeps treatment notes, inventory, and invoices on one record, so your team can raise, submit, and track claims from one place.

Book a demo

Conclusion

A4928 is a small code with two traps: a unit of 20 masks and a pricing status that rarely pays on its own. For dialysis patients, the ESRD bundle already covers the masks, so a separate supplier claim is not paid.

Bill A4928 only where a plan lists it as payable, report whole packs, and keep the count in the record. That approach keeps mask lines out of your denial queue.

Clean supply claims start with details recorded at the point of care. Book a demo to see how Pabau keeps notes, stock, and claims in one place.

Continue your research

Need a denial management framework? Denial codes in medical billing walks through the most common CARC codes and how to resolve each one systematically.

Billing other dialysis supplies? HCPCS code A4930 covers sterile gloves, reported per pair.

Want to understand the full billing cycle? What is revenue cycle management covers the end-to-end process from eligibility verification to payment posting.

Looking for eligibility verification guidance? Insurance eligibility verification explains how to confirm coverage before the appointment.

Frequently asked questions