HCPCS code A4709 – Acid concentrate solution for hemodialysis

Key takeaways

HCPCS code A4709 describes acid concentrate solution for hemodialysis, and each billed unit equals one gallon.

Medicare bundles A4709 into the ESRD PPS payment, so the dialysis facility is paid for it in-center and at home.

A DME supplier that ships acid concentrate to a Medicare home patient is paid by the ESRD facility, not by Medicare.

Medicaid and commercial payers set their own rules, so check the state program or the contract before billing A4709 separately.

Insurer-specific price lists in Pabau’s practice software keep A4709 off Medicare claims and on the contracts that pay for it.

What is HCPCS code A4709?

HCPCS code A4709 is the Healthcare Common Procedure Coding System Level II code for acid concentrate, solution, for hemodialysis, per gallon. The Centers for Medicare and Medicaid Services (CMS) maintains the code set.

A4709 sits in the A-code section for medical and surgical supplies. It falls inside the A4706-A4714 run of dialysis concentrate and water codes. Each unit equals one gallon of acid concentrate solution. Five gallons supplied means five units, however many treatments those gallons cover.

What A4709 covers and what it does not

A4709 covers acid concentrate supplied as a solution for hemodialysis, counted in gallons. However, it does not cover the other concentrates or the water used to make dialysate.

• Bicarbonate concentrate: the solution form is A4706, billed per gallon. The powder form is A4707, billed per packet.
• Acetate concentrate: A4708 covers acetate concentrate solution for hemodialysis, per gallon. It is a different product, so it is not an acid concentrate.
• Treated water: A4714 covers deionized, distilled or reverse osmosis water for peritoneal dialysis, per gallon. It is neither a concentrate nor a hemodialysis code.
• Peritoneal dialysis solutions: dialysate for peritoneal dialysis has its own codes, starting at A4720.

Clinical context: How acid concentrate works in hemodialysis

Hemodialysis removes waste and excess fluid by passing blood along a membrane, with dialysate flowing on the other side. The machine makes that dialysate by mixing acid concentrate, bicarbonate concentrate and treated water in a set ratio.

Acid concentrate supplies most of the electrolytes, such as sodium, potassium, calcium and magnesium, often with dextrose. It also contains a small amount of acid, usually acetic or citric acid. This acid keeps the mixed dialysate at the right pH.

The dialysis prescription sets the potassium and calcium levels, so a program may stock several formulations. Even so, each formulation supplied as a solution still reports under A4709, counted in gallons.

Is A4709 separately payable under Medicare?

No. Medicare does not pay A4709 separately to anyone. Since January 1, 2011, the ESRD PPS has paid the ESRD facility one bundled rate per dialysis treatment. That rate covers dialysis supplies.

The bundle applies at home as well as in-center. The Medicare Claims Processing Manual, Chapter 8 says the payment covers supplies used in the ESRD facility or at a patient’s home. As a result, other suppliers must look to the ESRD facility for payment.

CMS publishes the ESRD PPS consolidated billing list so contractors can edit claims. On the CY 2026 list, A4709 appears among the DME ESRD supplies not payable to DME suppliers. As a result, consolidated billing edits deny a supplier claim for a Medicare ESRD patient.

How A4709 is paid for home and in-center hemodialysis

Before 2011, home dialysis patients could choose Method II, which let a DME supplier bill Medicare directly for home supplies. The ESRD PPS ended that route, so home supplies now flow through the facility that runs the patient’s home program. The diagram below traces who gets paid in each setting.

• In-center hemodialysis: the facility buys the acid concentrate, and its cost sits inside the per-treatment ESRD PPS payment.
• Home hemodialysis: the facility that supervises the home program must furnish the concentrate, directly or under arrangements. It bills the home treatments on its institutional claim, type of bill 72X with condition code 74.
• DME suppliers: a supplier may still deliver concentrate to a patient’s home under an arrangement with the facility. The facility pays the supplier, and Medicare does not.

The patient still owes any unmet Part B deductible and the 20% coinsurance on the facility’s dialysis payment.

HCPCS code A4709 fee schedule and reimbursement in 2026

A4709 has no Medicare DMEPOS fee schedule amount to look up. CMS treats it as not separately priced by Part B, because its payment sits inside the ESRD PPS bundle.

The facility’s payment is the ESRD PPS per-treatment rate, which CMS updates each calendar year through its ESRD PPS rulemaking. In other words, A4709 does not raise that rate. Money for the concentrate moves in two other places:

• Facility and supplier contracts: the price per gallon the ESRD facility agrees with its concentrate supplier. This is a commercial term, not a Medicare rate.
• Non-Medicare payers: some Medicaid programs and commercial plans may allow a separate line for A4709. The rate then comes from the state fee schedule or the payer contract.

Medicaid and commercial payer considerations

Medicaid handling varies by state. Some programs follow Medicare and pay dialysis supplies through a facility rate. Others list supply codes on a fee schedule. Check the state Medicaid fee schedule and provider manual before you bill A4709 to Medicaid.

Commercial and Medicare Advantage plans set their own terms. A contract may pay a per-treatment case rate that includes supplies, or it may allow itemized supply lines. Confirm the contract’s dialysis terms in writing before you bill A4709 as its own line.

Documentation requirements for A4709

Because Medicare pays the facility, the records sit with the ESRD facility’s home program and its supplier. Good medical billing compliance practice keeps four records aligned:

1. Dialysis prescription: the physician’s order sets the dialysate formulation, including potassium and calcium levels. It decides which acid concentrate the patient receives.
2. Qualifying diagnosis: the facility claim carries the diagnosis that supports dialysis, such as ICD-10-CM N18.6 for end stage renal disease.
3. Delivery and quantity log: each shipment records the formulation, the number of gallons and the delivery date. These figures should also match the supplier’s invoice to the facility.
4. Supply arrangement: the written agreement between the facility and any outside supplier. It shows who furnishes the concentrate and who pays for it.

Where a non-Medicare payer allows separate billing, the units on the claim must match the gallons in the delivery log. Otherwise, a mismatch between the two is an easy audit finding.

Applicable modifiers for A4709

No modifier makes A4709 separately payable by Medicare for an ESRD patient. Modifiers report circumstances, but they cannot override a consolidated billing edit.

Medicaid and commercial payers may set their own modifier rules for supplies. In that case, follow the payer’s billing manual where it allows A4709 as a separate line.

Related dialysis supply codes: A4706 through A4714

A4709 sits in a short run of dialysis concentrate and water codes. Each one describes a different product or unit, so the code should match what was supplied.

All five codes appear on the CY 2026 consolidated billing list as supplies not payable to DME suppliers. For this reason, Medicare bundles each of them into the facility payment.

Common reasons A4709 claims are denied

Most A4709 denials come from billing an item that Medicare has already paid inside the bundle. Clearing these patterns out of fee tables cuts the work that lands in your denial management workflows.

• Consolidated billing denial: a DME supplier bills Medicare for concentrate sent to an ESRD patient. Fix: invoice the ESRD facility under the supply arrangement instead.
• Home setting treated as separately payable: the billing team assumes home hemodialysis sits outside the bundle. That was the rule under Method II. Fix: remove A4709 from Medicare fee tables for home patients too.
• Units counted per treatment: the line counts sessions instead of gallons. Fix: bill the gallons supplied, taken from the delivery log.
• Wrong sibling code: acid concentrate billed as A4708 acetate concentrate, or bicarbonate billed as A4709. Fix: code each formulation to its own descriptor.
• No contract basis: the supply line goes to a commercial plan that pays dialysis as a case rate. Fix: confirm the contract terms before adding A4709 to the claim.

Review the common denial codes to see how payers label these rejections. A clean claim check before submission also catches most of them.

How Pabau supports ESRD supply coding and claim accuracy

Bundled supply codes cause repeat denials when a billing team keeps them in a fee table. The team then submits them by habit. Each failed claim takes time to investigate, and the same error returns next cycle.

Pabau, the practice software we build, gives your team claims software for billing teams. It covers electronic claim submission, eligibility checks, claim status tracking and ERA posting. Insurer-specific price lists let your team leave A4709 off the Medicare list. Your team can then keep it where a contract pays for it.

The result is fewer rejected claims and a clear record of which payers pay for which dialysis supplies.

Keep bundled dialysis supplies off the wrong claims

Pabau’s insurer-specific price lists keep bundled codes such as A4709 off Medicare claims. Your team bills each supply only where the payer pays for it.

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Conclusion

Under Medicare, A4709 is a cost inside the ESRD facility’s bundled payment, not a line on a supplier claim. That holds for home hemodialysis as much as for in-center care.

Your next step is to audit fee tables, supply contracts and billing defaults for leftover Medicare A4709 billing. Route supplier invoices to the facility, and keep separate billing for Medicaid or commercial contracts that clearly allow it. Book a demo to see how Pabau’s insurer-specific price lists keep A4709 on the right claims.

Continue your research

Coding other supplies for a home hemodialysis program? HCPCS code A4680 explains how the activated carbon filter used in dialysis water treatment is paid under the same ESRD bundle.

Billing a dialysis supply with no named code? HCPCS code A4913 covers miscellaneous dialysis supplies and why Medicare pays them inside the facility rate.

Want to see how electronic claims flow through a clearinghouse? 837 file submission guide walks through the electronic claim format used for professional and institutional claims.

Looking to tighten your revenue cycle from order through payment? Revenue cycle management fundamentals covers the end-to-end billing process for practices managing complex payer mixes.

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