What Is the MICR Line on a Check?

Check printers print the MICR line on every check in the same machine readable font using magnetic ink. The line is uniform across the country so financial institutions, using high-powered machines, can read it and accurately process massive numbers of checks. The printing standards were established by the American Bank Association (ABA) and are enforced by the American National Standards Institute (ANSI).

The routing number, also known as the ABA number, is the first group of numbers on the line. The Federal Reserve Bank issues routing numbers to identify financial institutions with a federal or state charter. The routing numbers are essentially how financial institutions identify each other. Many financial institutions have different routing numbers for different types of transactions. You'll need to know routing numbers when you set up a direct deposit, automated clearinghouse transaction or an electronic fund transfer (EFT).

The account number is always the second group of numbers on the MICR line. It's the same account number you got when you set up the account.

Not all MICR lines and checks are the same. If the check is longer than 6.5 inches, the MICR will have a third line that shows the check number. This is the same check number that appears in the upper right-hand corner of the check, only that one is in regular ink.