skip to content
Thank you for visiting First Coast Service Options' Medicare provider website. This website is intended exclusively for Medicare providers and health care industry professionals to find the latest Medicare news and information affecting the provider community.
To enable us to present you with customized content that focuses on your area of interest, please select your preferences below:
Select which best describes you:
Select your location:
Select your line of business:
This website provides information and news about the Medicare program for health care professionals only. All communication and issues regarding your Medicare benefits are handled directly by Medicare and not through this website. Information for Medicare beneficiaries is only available on the website.
En Español
Text Size:
Send a link to this page
[Multiple email adresses must be separated by a semicolon.]
Last Modified: 12/7/2017 Location: FL, PR, USVI Business: Part B

Avoiding RUC reason code CO 16 FAQ

Q: We received a returned unprocessable claim (RUC) with claim adjustment reason code (CARC) CO 16. What steps can we take to avoid this RUC code?
CO 16: Claim/service lacks information or has submission/billing error(s) which is/are needed for adjudication. Do not use this code for claims attachment(s)/other documentation. At least one Remark Code must be provided (may be comprised of either the NCDPD Reject Reason Code or Remittance Advice Code that is not an ALERT.) Note: Refer to the 835 Healthcare Policy Identification Segment (loop 2110 Service Payment Information REF), if present.
A: CARC CO 16 applies to various scenarios regarding missing or invalid information on the claim. To avoid delay in payment, submit a corrected claim. Claims that are returned as unprocessable cannot be appealed, as an initial determination was not made. For more information, click here.
Refer to claim submission guidelines for additional information.
Refer to the Centers for Medicare & Medicaid Services (CMS) guidelines for completion of form CMS-1500 in the Medicare Claims Processing Manual (100-04), Chapter 26 external pdf file.
Please review the remittance advice remark codes (RARCs) pertaining to your claim and then click on the applicable topic below for steps you can take to avoid the RUC:
Beneficiary name and/or Medicare number
MA61: Missing/incomplete/invalid Social Security number or health insurance claim number (HICN).
MA36: Missing /incomplete/invalid patient name.
MA27: Missing/incomplete/invalid entitlement number or name shown on the claim.
Review and make a copy of patient’s Medicare card for file and verify eligibility. For additional information, click here for beneficiary eligibility Frequently Asked Questions (FAQs).
Enter patient’s name on claim as indicated on Medicare card.
Include spaces and special characters if indicated on Medicare card. Exception: ABILITY | PC-ACE™ software currently does not accept special characters; enter space instead.
Enter patient’s Medicare number as indicated on Medicare card.
Billing entity/provider
N256: Missing/incomplete/invalid billing provider/supplier name.
N257: Missing/incomplete/invalid billing provider/supplier primary identifier.
N258: Missing/incomplete/invalid billing provider/supplier address.
MA112: Missing/incomplete/invalid group practice information.
Refer to Item(s) 33 and/or 33A on the claim form. These are required fields. Enter the billing provider/supplier name, address and zip code in Item 33, and the billing provider’s, or group’s, NPI in Item 33A.
Charges on claim
M79: Missing/incomplete/invalid charge.
Refer to Item 24F on the claim form. Medicare does not pay for services when a charge is not indicated. Enter a charge for each service listed on the claim..
CLIA certification number
MA120: Missing/incomplete/invalid CLIA certification number.
Refer to Item 23 on the claim form. Enter the ten-digit CLIA certification number for laboratory services billed.
Click here external link for procedures that require a CLIA certification.
Date range not valid with units submitted
M52: Missing/incomplete/invalid –from- date(s) of service.
N345: Date range not valid with units submitted.
Refer to Item(s) 24A and/or 24G on the claim form. Ensure date(s) of service (DOS) correspond(s) to the number of units/days billed. If billing for more than one unit on a single day, services may need to be itemized, one per line.
Facility ZIP code or state code
N104: This claim service is not payable under our claims jurisdiction area. You can identify the correct Medicare contractor to process this claim/service through the CMS website at external link.
Refer to Item 32 on the claim form. Service facility information is used to price claims. Enter the state code and ZIP code on the claim.
Click here external link to see if a 9-digit ZIP code is needed for the facility.
The state code should be referred to as the province code for providers in U.S. Virgin Islands.
Click here external link to review the Contractor Directory - Interactive Map to access state-specific CMS contractor contact information.
Facility/laboratory name and/or address
N294: Missing/incomplete/invalid service facility primary address.
MA114: Missing/incomplete/invalid information on where the services were furnished.
Refer to Item 32 on the claim form. Service facility information is used to price claims. Enter the service location name and complete address on the claim.
Enter the service location name, street address, city, state and a valid ZIP code in item 32.
The location where the service was rendered is required for all place of service (POS) codes.
If additional entries are needed, separate claim forms must be submitted.
If required by Medicare claims processing policy, enter the NPI of the service facility in item 32a.
Purchased service/primary provider identifier
N270: Missing/incomplete/invalid other provider primary identifier.
N283: Missing/incomplete/invalid purchased service provider identifier.
Effective for claims submitted with a receipt date on and after October 1, 2015, billing physicians and suppliers must report the name, address, and NPI of the performing physician or supplier on all anti-markup and reference laboratory claims, even if the performing physician or supplier is enrolled in a different contractor’s jurisdiction. Physicians and suppliers may no longer indicate their own information when the laboratory service(s) were purchased..
Enter the valid performing physician or supplier’s NPI in item 32a.
Enter the actual performing physician/supplier’s name, address and ZIP code in item 32.
Click here for additional guidance on billing anit-markup and reference laboratory claims.
Note: Do not combine non-referred (i.e., self-performed) and referred services on the same CMS 1500 claim form. Submit two separate claims, one claim for non-referred tests and the other for referred tests.
ICD diagnosis codes
M76: Missing/incomplete/invalid diagnosis or condition.
M81: You are required to code to the highest level of specificity
Refer to Item 21 on the claim form. Enter the ICD Indicator and diagnosis code on the claim.
Enter the appropriate ICD Indicator as a single digit between the vertical, dotted lines.
Indicator ‘9’ is used for ICD-9-CM diagnosis codes.
Indicator ‘0’ is used for ICD-10-CM diagnosis codes.
Enter up to 12 diagnosis codes, in priority order. The diagnosis codes must be coded to the highest level of specificity.
Use the most current year's ICD-9-CM or ICD-10-CM codes, depending on the date(s) of service.
Do not insert a period in the ICD-9-CM or ICD-10-CM codes.
Example: Diagnosis code 285.21 is entered as 28521, without a period or space.
Reminder: Do not report ICD-10-CM codes for claims with date(s) of service prior to October 1, 2015.
Incorrect claim form/format
N34: Incorrect claim form/format for this service.
Refer to Items 11b, 12, 14, 16, 18, 19, 24a and 31 on the claim form. You have the option to enter either a 6-digit (MMDDYY) or 8-digit (MMDDCCYY) date. However, the date format you choose must be consistent throughout the claim.
e.g., if you choose the 6-digit format for the first date field, then that 6-digit format must be used in all subsequent date fields in the provider portion of that particular claim. Conversely, if you use the 8-digit format for the first date field, then you would continue to use the 8-digit format for the remainder of the date fields in the provider portion of that particular claim.
Ordering or referring physician name, qualifier and/or NPI
N264: Missing/incomplete/invalid ordering provider name.
N265: Missing/incomplete/invalid ordering provider primary identifier.
N276: Missing/incomplete/invalid other payer referring provider identifier.
N285: Missing/incomplete/invalid referring provider name.
N286: Missing/incomplete/invalid referring provider primary identifier.
Refer to Items 17 and 17B on the claim form. Enter the name and qualifier in Item 17, and the NPI in Item 17B. For additional information, refer to ordering/referring provider FAQs.
Physician/supplier signature
MA81: Missing/incomplete/invalid provider/supplier signature.
Refer to Item 31 on the claim form. The signature of the physician or non-physician practitioner is required. The following formats are acceptable.
Actual signature
“Signature on file” notation (if applicable)
Computer-generated signature
Primary or secondary payer information
MA83: Did not indicate whether Medicare is the primary or secondary payer.
Refer to Item 11 on the claim form. This is a required field. By completing this item, a physician/supplier acknowledges that he/she made a good faith effort to determine whether Medicare is the primary or secondary payer.
If Medicare is primary, enter the word “NONE.”
If Medicare is secondary, enter the insured’s policy or group number, and precede with Items 11a -11c.
Note: Items 4, 6 and 7 must also be completed.
Procedure codes
M51: Missing/incomplete/invalid procedure code(s).
Refer to Item 24D on the claim form. Before submitting your claim, ensure you use the most current year's Current Procedural Terminology (CPT®) and/or Healthcare Common Procedure Coding System (HCPCS) code(s).
Check code status via our fee schedule lookup tool  to confirm the procedure code is valid for Medicare. Be aware that code status may change, so a procedure code that was previously valid for Medicare may no longer be valid.
If the procedure code has an “I” status, the procedure code is not valid for Medicare and should not be billed unless documentation is needed for a secondary payer or supplemental plan.
Click here for additional information regarding procedure codes.
Rendering physician NPI
N290: Missing/incomplete/invalid rendering provider primary identifier.
MA112: Missing/incomplete/invalid group practice information.
Refer to Item 24J on the claim form. If the rendering provider is linked to the group, enter the individual practitioner’s NPI in the unshaded portion of this field.
list item Please use your browser's back button to return to the referring page.
Source: First Coast Education Action Team
First Coast Service Options (First Coast) strives to ensure that the information available on our provider website is accurate, detailed, and current. Therefore, this is a dynamic site and its content changes daily. It is best to access the site to ensure you have the most current information rather than printing articles or forms that may become obsolete without notice.