If you need to make a repayment to Medicare and Palmetto GBA is your MAC, be sure to include your NPI on your check. "Some submitted checks were not processed timely due to the lack of requested information," Palmetto notes in an e-mail message to providers. To make sure your check is processed in a timely manner you should always include your National Provider Identifier number on it. And "if you are submitting a check in response to a letter you received from Palmetto GBA or the Recovery Audit Contractors (RACs), always attach a copy of the letter when sending the check," Palmetto says.