CO 253 denial code

What CO-253 means

CO-253 is not a denial. It reports the federal sequestration reduction: a 2% cut to Medicare fee-for-service payments required by the Budget Control Act, applied to claims since April 2013. The group code CO (contractual obligation) tells you the amount is a write-off. The patient owes nothing extra because of it.

The math matters for posting. Medicare takes 2% of its payment, not 2% of the allowed amount. Example: allowed amount $100, patient has met the deductible, coinsurance is $20. Medicare would pay $80. Sequestration takes 2% of that $80, so the check is $78.40 and the remittance shows CO-253 for $1.60. The patient’s coinsurance is still $20; it is calculated before the reduction and is not affected.

Common causes

You will see CO-253 on nearly every paid Medicare fee-for-service claim. It is routine. Situations worth noting:

1. Standard Part B claims: the 2% comes off Medicare’s 80% share after deductible and coinsurance.
2. Medicare Secondary Payer claims: sequestration applies to whatever Medicare pays as secondary, so the amount is smaller and easy to misread when reconciling against an OA-23 adjustment.
3. Medicare Advantage plans: many apply an equivalent reduction under their CMS contracts, but how they report it varies. Check the plan’s remittance guidance.

The only real problem scenario is a posting error on your side: staff who treat CO-253 as a denial and rebill it, or who shift it to the patient.

How to fix and resubmit

There is nothing to fix on the claim. The workflow is about posting it correctly:

1. Post the CO-253 amount as a contractual adjustment against the claim, the same way you post CO-45.
2. Never transfer the amount to the patient. CO group adjustments cannot be balance-billed.
3. Do not resubmit or appeal. The reduction will apply again on reprocessing.
4. If your practice management system supports it, set an auto-post rule for CARC 253 so it never lands in a work queue.
5. If CO-253 appears on a claim type where it should not (rare), contact your MAC before touching the claim.

When you are estimating expected reimbursement (for example, when checking rates with an RVU calculator), remember to model the 2% off Medicare’s portion, or your expected-payment variance reports will flag every Medicare claim as a short payment.

How to prevent it

You cannot prevent sequestration; it is set by federal law, and CMS applies it until Congress changes it. Prevention here means preventing bad handling:

• Train new billers that CO-253 is an expected adjustment, not a denial to work.
• Build the 2% into fee schedule expectations and contract-variance rules so reconciliation runs clean.
• Audit patient statements periodically to confirm sequestration amounts are never passed to patients.
• Watch MAC bulletins. Sequestration has been suspended and phased back in before (it paused during the COVID-19 public health emergency), so the percentage in your posting rules needs an owner who keeps it current.