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N818 Remark Code: Claim Dates Don't Match EVV Records

N818 means the dates of service on the claim don't match the visit records in the Electronic Visit Verification (EVV) system. It appears mainly on Medicaid personal care and home health claims, where the payer checks billed dates against the verified visits.

Quick facts

Code
N818 (RARC N818)
Status
Active In use since July 1, 2019.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The service was denied for a mismatch the provider must resolve. It is not billable to the member.
Official description
Claims Dates of Service do not match Electronic Visit Verification System.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N818 means

Home and community-based services paid by Medicaid increasingly depend on Electronic Visit Verification. The caregiver’s device records the date, start and end times, location, and service for each visit, and the state or managed care plan compares claims against those records before paying.

N818 is the result of that comparison failing on dates: the claim bills a service on a date that the EVV system doesn’t show, or shows differently. It is a data-matching issue and usually comes with CARC 16. Rules are set by each state Medicaid program, so exact matching logic varies.

Common causes

  • Keying errors in the claim’s date of service.
  • Overnight visits that start on one date and end on the next, recorded differently in EVV and the claim.
  • Late or missed clock-ins, where the caregiver’s visit was recorded on a different day or entered manually later.
  • Aggregated billing, where a week of visits was billed with a date range that doesn’t line up with individual EVV entries.
  • Time zone or sync problems in the EVV device or aggregator.

How to fix it

  1. Pull the EVV visit log for the member and the billing period.
  2. Compare it line by line with the claim’s dates and the caregiver’s documentation.
  3. Correct the source of the error. Fix the claim date if it was wrong; if the EVV record was wrong, use your system’s visit maintenance process with the proper reason code.
  4. Resubmit once the records match, following the state’s rules for corrected claims, such as resubmission code 7 in box 22.

How to prevent it

  • Run an EVV-to-claim match before billing, and hold any service without a matching visit.
  • Train caregivers on clocking in and out on time, especially for overnight shifts.
  • Bill visits by date in a way that mirrors how EVV records them.

Codes that may appear with N818

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim has a billing error; N818 says the dates conflict with EVV data.
  • CO-A1 (Claim/Service denied.): A general claim denial where the remark explains the reason.
  • N821 (Electronic Visit Verification System visit not found.): No EVV visit was found at all for the service billed.
  • N820 (Electronic Visit Verification System units do not meet requirements of visit.): The EVV visit exists but its units don't support what was billed.
  • N913 (More than one Electronic Visit Verification record exists for the date and time of this service.): More than one EVV record exists for the same date and time.

N818 FAQ

What is Electronic Visit Verification?

EVV is an electronic system that records when and where a home visit happened and who provided it, typically using a phone app or device. Federal law requires state Medicaid programs to use EVV for personal care services and home health care services.

Which record is correct, the claim or EVV?

It depends. Sometimes the claim has a typo; sometimes the caregiver clocked in on the wrong day. Check the visit notes and timesheets, then correct whichever record is wrong using your state's rules.

Can I change EVV records after the visit?

Most EVV systems allow visit maintenance with a documented reason code, within limits set by the state. Excessive edits may draw audit attention.