Ending AX modifier requirements for acute kidney injury (AKI) and end stage renal disease (ESRD)

Effective July 1, 2026, new billing guidelines apply related to billing the AX modifier and instructions for hemodiafiltration and AKI claims. 

• ESRD facilities do not need to submit the AX modifier on claims eligible for certain add-on payment adjustments under the ESRD PPS

• ESRD facilities must adhere to new billing instructions for hemodiafiltration and AKI claims.

There are several add-on payment adjustments under the ESRD PPS, which we include in the single per-treatment payment: 

• Transitional drug add-on payment adjustment (TDAPA) for certain new renal dialysis drugs and biological products 

• Transitional payment for new and innovative equipment and supplies (TPNIES) for renal dialysis 

The TDAPA applies to certain new renal dialysis drugs and biological products that we do not include in the ESRD PPS base rate and for certain drugs and biological products in existing ESRD PPS functional categories. The first drugs we paid the TDAPA for were calcimimetics in 2018. The TPNIES applies to certain new and innovative equipment that are not capital-related assets (CRAs) except CRAs that are home dialysis machines for a single patient.

AX modifier updates

Starting July 1, 2026, do not report the AX modifier for:

• New renal dialysis drugs and biological products eligible for the TDAPA

• Innovative equipment and supplies eligible for the TPNIES

• CRAs eligible for the CRA TPNIES 

CMS will apply the pricing instructions for the:

TDAPA when you report a HCPCS code on the TDAPA list with revenue code 0636. 

• TPNIES when you report a HCPCS code on the TPNIES list with revenue code 027X.

• CRA TPNIES when you report a HCPCS code on the CRA TPNIES list with 1 of these revenue codes: 

• 0823 – Hemodialysis home equipment 

• 0833 – Peritoneal home equipment 

• 0843 – CAPD home equipment 

Unless instructed, do not bill any renal dialysis services with the AX modifier for dates of services on or after July 1, 2026. 

These modifications to the AX modifier don’t impact prior and remaining TDAPA, TPNIES, and CRA TPNIES billing guidance. These changes don’t impact payments for renal dialysis services you provide to AKI patients for which you shouldn’t report with the AX modifier.

AKI and hemodiafiltration  

Starting July 1, 2026, we require ESRD facilities to:

• Use condition code 74 when billing AKI claims for dialysis in the home setting.

• Use either condition code 76 or 87, as appropriate, when billing AKI claims for training or re-training for AKI home dialysis and self-dialysis.

• Use revenue code 0829 and CPT code 90999 when billing for hemodiafiltration. 

• We will pay hemodiafiltration claims you bill with revenue code 0829 at the same rate as hemodialysis claims.

• Continue to bill for only 1 treatment per day and not to bill for hemodialysis and hemodiafiltration on the same date of service.

• Use both condition code 76 and 84 when billing for back-up in-facility dialysis for AKI patients. 

Claims will be returned if submitted with more than 1 hemodialysis treatment on the same date of service on type of bill 072X with revenue code 0821 or 0829. 

Condition codes

Revenue codes 

HCPCS

Report the appropriate HCPCS codes, when applicable. 

Modifiers

References

• CMS IOM Pub. 100-04 Medicare Claims Processing Manual, Chapter 8 

• Medicare Learning Network (MLN) Article: MM14354: Acute Kidney Injury & ESRD Billing: Ending the AX Modifier Requirement

• End-Stage Renal Disease (ESRD) Billing Requirements