The Group Code is combined with the ANSI reason code to demonstrate who has financial responsibility for the amount. PR - Patient Responsibility This shows what amount the beneficiary or his/her supplemental insurer is responsible for. PR amounts, including the deductible and coinsurance, are totaled in the Patient Responsibility field at the end of each claim. If you already collected an amount from a beneficiary for this claim in excess of the Patient Responsibility total prior to receipt of the remittance notice, you are required by law to refund that excess to the beneficiary. CO - Contractual Obligation CO is always used to identify excess amounts for which the law prohibits Medicare payment and absolves the beneficiary of any financial liability, such as participation agreement violation amounts, limiting charge violations, late filing penalties, or amounts for services not considered to be reasonable and necessary. You may not hold a beneficiary financially responsible for any adjustments identified with this group code. OA - Other Adjustment Used when neither PR nor CO applies, such as with the reason code message that indicates the bill is being paid in full. CR - Correction to or Reversal of a prior decision Demonstrates when there is a change to the decision on a previously adjudicated claim, perhaps as result of a subsequent reopening. CR explains the reason for a change and is always used with PR, CO, or OA to show revised information.