835 Denial Combination
CO-16+N257
Contractual Obligation · Service-Line Level Adjustment
What This Combination Means
The claim was denied because information needed to adjudicate was missing or incomplete — specifically, the rendering provider's NPI is absent or invalid. N257 confirms the remark: information identifying the rendering provider is not on file. This is one of the most common 835 denials and is always correctable.
95%
Appeal Success
3-7 days
Avg. Resolution
Easy
Difficulty
Yes
Appealable
Step-by-Step Resolution
Steps tailored specifically to this CO-16+N257 combination — not generic advice.
- 1
Pull the original 835 ERA and confirm the CAS segment reads CO-16 with remark N257 on the specific service line.
- 2
Log into NPPES (nppes.cms.hhs.gov) and verify the rendering provider has an active Type 1 (individual) NPI.
- 3
Compare the NPI on your claim to NPPES — even a single digit error causes this denial.
- 4
Correct the rendering provider NPI in your practice management system and resubmit as a corrected claim (frequency type 7).
- 5
If the payer has a provider file, confirm the NPI is enrolled and credentialed with that specific payer.
- 6
Resubmit with corrected NPI within the payer's timely filing window (typically 90–365 days from DOS).
Specialty Context
How CO-16+N257 typically presents across different practice types.
Dental
Verify the treating dentist's individual NPI (Type 1) is in Box 53 of the ADA claim form. Group NPI alone in Box 54 is insufficient for most payers.
Medical
Check that the rendering provider NPI in Loop 2310B NM109 (837P) matches the provider's NPPES record exactly. CMS requires the individual NPI, not the billing group NPI.
Behavioral Health
Confirm the clinician's individual NPI is submitted in the rendering provider loop. Many EHR systems default to the practice NPI — override this for every claim line.
Individual Code References
View the standalone definition for each code in this combination.
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