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N108 Remark Code: Missing or Invalid Upgrade Information

N108 means the claim was missing, or had incomplete or invalid, information about an upgrade. It typically applies to durable medical equipment or supplies where the item furnished was more deluxe than the one the payer considers medically necessary.

Code: N108 (RARC N108)
Status: Active In use since January 31, 2002; last modified February 28, 2003.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): The claim could not be processed correctly without the upgrade details. Correct and resubmit rather than billing the patient.
PR (Patient Responsibility): Once the upgrade is properly reported, the patient may owe the difference for the upgraded item if they agreed to it in advance.
Official description: Missing/incomplete/invalid upgrade information.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N108 means

When a patient chooses, or a supplier provides, equipment that goes beyond what is medically necessary, the claim has to show both what was delivered and what the payer would have covered. That is the upgrade information. N108 means the payer could not tell how the upgrade was structured because the details were absent or did not make sense together.

N108 usually appears with CARC 16. It is most common on DME supplier claims.

Common causes

The upgraded item was billed without the companion line for the standard, medically necessary item.
Upgrade modifiers were missing, reversed between lines, or used with codes that do not fit.
An upgrade modifier was reported, but the claim gave no indication that an advance notice was obtained.
The charges on the paired lines did not reflect the difference between the standard and upgraded items.

How to fix it

Review the delivery ticket and order to confirm what was furnished and what was medically necessary.
Rebuild the claim lines according to the payer’s upgrade instructions, including both items and the correct modifiers on each (CMS-1500 box 24D or the corresponding 837P service line).
Confirm the advance notice is signed and on file if you intend to collect the difference from the patient.
Submit a corrected claim with resubmission code 7 in box 22 and the original claim number, or a new claim if the payer rejected the original.

How to prevent it

Train intake staff to recognize upgrade requests and trigger the notice and billing workflow at the time of order. Supplier billing templates that always generate the paired lines for upgraded items prevent most N108 denials. See how missing-information denials work for the broader pattern.

Codes that may appear with N108

CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information needed for adjudication; N108 specifies upgrade information.
CO-4 (The procedure code is inconsistent with the modifier used.): The procedure code is inconsistent with the modifier, which can happen when upgrade modifiers are missing or mismatched.

N172 (The patient is not liable for the denied/adjusted charge(s) for receiving any updated service/item.): States that the patient is not liable for charges tied to an upgraded item.
N124 (Payment has been denied for the/made only for a less extensive service/item because the information furnished does not substantiate the need for the…): Payment made only for a less extensive item, with the patient liable after written notice.
N125 (Payment has been (denied for the/made only for a less extensive) service/item because the information furnished does not substantiate the need for…): Payment made only for a less extensive item, with a refund owed to the patient.

N108 FAQ

What is an upgrade in DME billing?

An item with features beyond what is medically necessary for the patient, such as a more deluxe model. The payer pays for the standard item, and the extra cost is handled under the upgrade rules.

Which modifiers are involved?

For Medicare DME, suppliers commonly use GA (advance notice on file) with the upgraded item and GK on the medically necessary item, or GL when the upgrade is provided at no charge without an advance notice. Other payers may have their own conventions.

Can the patient be charged for the upgrade?

Only if the patient was informed in writing beforehand and agreed to pay the difference, following the payer's notice rules.

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