Skip to main content

N231 Remark Code: Invalid Intraocular Lens Invoice

N231 means the invoice or statement sent to certify the actual cost of an intraocular lens (IOL), less any discounts, and/or the type of lens used was incomplete or invalid. The payer needs it to price the lens, usually after cataract surgery.

Quick facts

Code
N231 (RARC N231)
Status
Active In use since August 1, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The lens charge was denied or held because the cost documentation was not usable. The provider or facility corrects it; the patient is not liable for this.
  • PR (Patient Responsibility): Where a premium lens was chosen by the patient with proper notice, the non-covered upgrade portion may be patient responsibility; that is separate from the invoice problem.
Official description
Incomplete/invalid invoice or statement certifying the actual cost of the lens, less discounts, and/or the type of intraocular lens used.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N231 means

When an intraocular lens is billed separately, commonly with a HCPCS V-code for the lens type, some payers price it based on what the provider actually paid. To do that, they ask for an invoice showing the net cost after discounts and identifying the lens. N231 says the invoice you sent did not do the job. The remark usually accompanies CARC 252.

Where invoices fall short

Reviewers typically check four things. A problem in any one can produce N231:

  • Net cost. The invoice shows list price, but not rebates, volume discounts, or other price reductions.
  • Lens identity. The model or lens type is missing, so the payer cannot confirm it matches the HCPCS code billed.
  • Linkage. Nothing ties the invoice line to this patient or surgery date, which matters when invoices cover many lenses.
  • Authenticity. The document is a quote, packing slip, or internal price list rather than a supplier invoice or statement.

How to fix it

  1. Get the supplier invoice covering the implanted lens, and identify the lens by model or serial or lot number from the operative record.
  2. Mark the relevant line and show the net price after discounts; attach a supplier statement if discounts are applied separately.
  3. Confirm the HCPCS code billed matches the lens type on the invoice.
  4. Send the invoice through the payer’s attachment channel with the claim reference, or submit a corrected claim with resubmission code 7 if the lens code or charge needs to change.

How to prevent it

Record the lens implant sticker or identifiers in the operative record and link them to purchasing records. Build an invoice packet template for lens claims so every submission includes net price, lens type, and a patient link.

Codes that may appear with N231

  • CO-252 (An attachment/other documentation is required to adjudicate this claim/service.): Documentation, the lens invoice, is required to price the claim.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim or its support has invalid information about the lens.
  • M130 (Missing invoice or statement certifying the actual cost of the lens, less discounts, and/or the type of intraocular lens used.): The IOL invoice or cost statement was missing entirely.
  • N232 (Incomplete/invalid itemized bill/statement.): An itemized bill or statement was incomplete or invalid.
  • MA111 (Missing/incomplete/invalid purchase price of the test(s) and/or the performing laboratory's name and address.): Missing or invalid purchase price for a purchased test, another cost-based pricing requirement.

N231 FAQ

Why does the payer need the lens invoice?

Some payers pay for the lens at acquisition cost instead of a fixed rate, so they need proof of what was actually paid for it after discounts and which lens was used.

What makes an IOL invoice invalid?

A list price without discounts, no lens model or type, a date or patient that does not tie to the surgery, or a quote instead of an actual invoice.

What if we buy lenses on consignment?

Provide the invoice or statement that shows the price charged for the specific lens implanted, including any rebates or discounts that apply.