The Federal Reserve and all banks require that checks be printed with MICR toner for ease of processing. As a check travels through the check clearing system, it passes through reader-sorters which send a magnetic charge to the check, allowing the machine to read the information contained within the MICR line. If a check or other negotiable document is printed with regular non-MICR toner, the reader/sorter will reject the check, resulting in a bank fee for the company that printed the document.