CO-160: injury or illness from an excluded activity.

What X12 says CARC 160 means

Injury/illness was the result of an activity that is a benefit exclusion.

CARC 160 · Start 09/30/2003, last modified 09/30/2007.

In plain terms: The payer says the injury or illness came from an activity its plan excludes from benefits.

What it means on a remittance

This is a cause-based denial. The payer reads the cause of the injury or illness from the claim or from records and finds it falls under an activity the plan excludes. The X12 text does not list the activities; those are defined in each plan or policy.

Typical causes

• An accident or cause-of-injury code or claim narrative that points at an activity the plan excludes.
• Records or an accident questionnaire that the payer read as showing an excluded activity.
• A cause-of-injury code entered incorrectly, so the claim describes a different activity from what happened.

These are common billing patterns, not a diagnosis of your claim. The remittance and the payer's policy decide.

What to check

1. Read the exact exclusion in the plan's benefit documents and compare it with what happened.
2. Check the cause-of-injury and accident-related fields on the claim against the record.
3. Look at the remark code on the same line for the payer's stated basis.
4. Ask the payer whether it sent a questionnaire about the injury that is still open.

Correct, resubmit or appeal

If a data-entry error put the wrong cause on the claim, submit a corrected claim. If the cause is right and you believe the exclusion does not apply, ask for review with the plan language and the record. If the exclusion applies, the payer contract and the patient's plan documents decide who owes the amount, so read them before you bill the patient.

Medicare dates that apply

A Medicare redetermination request must be filed within 120 calendar days from the date a party receives the notice of the initial determination; receipt is presumed 5 calendar days after the notice date unless there is evidence to the contrary (42 CFR 405.942(a)), and a late request can be considered for good cause (405.942(b)). Other payers set their own appeal windows in the contract or plan documents, so read the notice for the date. The tool above runs the date math.

Related codes

Other codes: See CARC 24 and the full lookup for other plan-coverage reasons.

Worked example (hypothetical)

A claim for emergency treatment is denied CO-160. The claim carried an external-cause code describing an activity the plan lists as excluded, but the record shows a different event. The biller corrects the cause code from the record and submits a corrected claim.

Sources

• X12: Claim Adjustment Reason Codes — code text, usage notes and dates (list dated 10/30/2026, retrieved 2026-11-02)
• 42 CFR 405.942 — eCFR, current through 2026-10-29 (retrieved 2026-11-02)

Code descriptions are X12 copyrighted material, quoted here only for the codes on this page and linked to the owner. For the full lists, use X12. The X12 text and the Medicare rule above were read from these pages on November 2, 2026. Causes, checks and examples are general billing practice written for this page, not X12 content. Payers revise code lists, contracts and policies, so confirm anything that affects a claim or a deadline with the payer.