The Routing Transit Number on a check, also known as the R/T Number or simply the Routing Number, is what identifies the financial institution at which the check writer’s account is located. Each bank or credit union in the United States has a unique nine-digit identifier that is printed on its customer’s checks, and which tells the bank of first deposit where to present the item for clearing. The routing transit number is usually immediately followed by the customer’s account number, then the sequential check number.
Routing and account numbers are printed in a standardized location at the bottom of the check, in either E13B font or CMC7 font, the two main character sets used in Magnetic Ink Character Recognition (MICR). The superior accuracy of MICR recognition makes the routing and account information suitable for rapid machine reading with very low error rates.
To enhance machine readability and reduce the possibility of errors, the beginning and and of the routing number are marked by a special character, as in the example at right. The end of the account number also has its own special character. A third special character (not shown) denotes the dollar value in cases where it is encoded on the front of the check — this is rare in the United States, but is sometimes required in other areas of the world.
Also note that, while checks in the United States have the same number of digits in their routing transit numbers, and all follow the same left-to-right format, formats in other countries may be different. These discrepancies are one reason why, for example, Canadian checks could not initially be cleared electronically in the U.S. system. Banking software around the world always has to be calibrated to account for the specific format used in the country in which it is deployed!