RARC N357: Time Frame Between This Service and a Related Service Not Met
RARC N357 means the required time frame between this service and a related service, procedure, or supply has not been met under the payer policy. It usually rides with CO-119 (benefit maximum reached) or CO-151/CO-16. The fix is verifying the dates of service and either correcting a date error or waiting out the interval.
- Type
- Informational (supplemental)
- Usually paired with
- CO-119, CO-151, or CO-16
- Fixable?
- Sometimes — only if a date is wrong
- Typical fix
- Verify dates; correct a keying error or wait out the interval
What does remark code N357 mean?
Official X12 text: "Time frame requirements between this service/procedure/supply and a related service/procedure/supply have not been met." In plain English: the payer has a minimum interval that must pass between two related services, and the claim you sent falls inside that window, so the second service will not pay yet.
ERA mini-example: 92014 (comprehensive eye exam, established patient) billed $135.00 pays $0.00 with CO-119 and N357. The payer allows one comprehensive exam per interval and the prior one was 40 days earlier — inside the required gap — so the repeat is too soon. Wait out the interval or prove the early repeat was necessary.
Which denial code does N357 come with?
Most often CO-119 (benefit maximum for this time period has been reached), since a timing rule reads as a period limit. On payers that treat it as unprocessable you may see CO-16 instead, prompting a date correction. The CARC states the financial impact; N357 clarifies the trigger was an interval between related services. Sort the pairing out in the denial code lookup.
How do you fix an N357 denial?
- Pull both dates: the current date of service and the related prior service the payer is measuring against.
- Check for a keying error first — a transposed or wrong date of service is the most common fixable cause. Correct it and resubmit.
- If the dates are right but the repeat was clinically required sooner, appeal with the note documenting medical necessity for the early service.
- If the interval genuinely was not met and no exception applies, hold the claim and rebill after the required time frame passes.
How do you prevent N357?
Load payer interval and frequency rules into your scheduling and scrubbing logic so a too-soon repeat is caught at booking, not after a denial. Have front-desk staff confirm the last date of a related service for procedures with known waiting periods, and give coders the relevant LCD intervals for high-volume codes. Tracking N357 by CPT shows which services keep getting scheduled inside their window so you can fix the workflow upstream.
Frequently asked questions
It depends entirely on the service and the payer. N357 flags that a minimum interval a payer requires between a service and a related one has not passed — for example, a follow-up procedure billed before the mandated waiting period after the initial one, or a supply refilled sooner than the schedule allows. The remark never states the number of days; you have to read the payer policy or LCD for the exact interval that applies.
Only when the interval actually was met and a date is wrong on the claim, or when documentation shows a clinically justified early repeat. If a date of service was keyed incorrectly, correct it and resubmit. If the second service was genuinely medically necessary sooner than the schedule, appeal with the note explaining why. If the interval truly was not met, the denial stands and there is nothing to bill the patient.
They are close cousins. A pure frequency edit caps how many times a service pays in a period; N357 is about the gap between two related services being too short. They often appear together — the CARC (such as CO-119) carries the "maximum reached" financial message while N357 explains the mechanism was a timing rule, not a raw count.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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