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N445 Remark Code: Missing Cost or Paid Amount Document

N445 means a document showing the actual cost or paid amount is missing. The payer prices the item or service based on what the provider actually paid, typically from an invoice, and cannot calculate payment without that document.

Quick facts

Code
N445 (RARC N445)
Status
Active In use since July 1, 2008.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): Payment is held or denied until proof of cost is supplied. The provider sends the document; the patient is not billed.
Official description
Missing document for actual cost or paid amount.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N445 means

Some items have no set price on a fee schedule. For those, payers often pay based on what the provider actually paid, sometimes with a percentage added. To do that, they need proof of that cost. N445 says the payer needed a document showing actual cost or the amount paid and did not receive one. It usually accompanies CARC 252 or CARC 16.

When payers ask for proof of cost

  • Implants and devices billed on surgical claims, particularly in workers’ compensation.
  • Not otherwise classified HCPCS codes for supplies, equipment, or drugs.
  • Items priced “by report” under a payer’s policy.
  • Items where the payer’s fee is a percentage of invoice under a contract.

How to fix it

  1. Find the invoice for the specific item: manufacturer, product, quantity, and net price after discounts.
  2. Match it to the claim line. Mark the invoice line that corresponds to the billed item, and make sure the quantity and units agree with the claim.
  3. Send it using the payer’s attachment process, such as an electronic attachment referenced on the claim or a paper submission with the claim number on each page.
  4. Resubmit or reconsider as the payer directs. If a corrected claim is required, use resubmission code 7 and the original claim number.

How to prevent it

Build a list of codes that each major payer prices at cost, and attach invoices to those claims automatically. Keep invoices in a system billing staff can reach, organized by item and date, because hunting for a paper invoice weeks later is where these claims stall. Note that the invoice should reflect the price actually paid, including rebates or discounts where the payer requires that.

Codes that may appear with N445

  • CO-252 (An attachment/other documentation is required to adjudicate this claim/service.): An attachment or other documentation is required; N445 identifies the cost or paid amount document.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information needed to adjudicate, here the cost basis for pricing.
  • CO-163 (Attachment/other documentation referenced on the claim was not received.): An attachment referenced on the claim was not received.
  • N446 (Incomplete/invalid document for actual cost or paid amount.): The cost or paid amount document was received but was incomplete or invalid.
  • N350 (Missing/incomplete/invalid description of service for a Not Otherwise Classified (NOC) code or for an Unlisted/By Report procedure.): The description of an unlisted or not otherwise classified item is missing or invalid, often requested alongside an invoice.
  • N26 (Missing itemized bill/statement.): An itemized bill or statement is missing.

N445 FAQ

What counts as a document for actual cost?

Usually a manufacturer or supplier invoice showing the item, quantity, and price paid. Some payers accept a purchase order or cost statement; check their requirements.

Which claims need it?

Commonly items with no fixed fee, such as implants, certain supplies, unlisted or not otherwise classified codes, and some drugs. Workers' compensation and some government programs frequently price these items at cost.

Can I send the invoice with the original claim?

Yes, and that is often the best approach. Reference it on the claim using the payer's attachment method so it is matched to the right claim.