MICR: What Is a Magnetic Ink Character Recognition Line?

What is a MICR line?

A MICR (Magnetic Ink Character Recognition) line is the string of characters printed at the bottom of a check that identifies the bank routing number, the account number, and the check number. The characters are printed with magnetic ink and special fonts so machines can read them reliably and so the checks are harder to forge.

How MICR works

• Magnetic ink: Characters are printed with magnetizable ink so a reader can detect their magnetic signal even if the surface is obscured by signatures, cancellation marks, or stamps.
• Special fonts: Two standardized fonts are used worldwide:
• E-13B — mainly used in North America, Australia, and the U.K.
• CMC-7 — used in many European and South American countries.
• Machine reading: MICR reader-sorter machines scan the magnetic signal and decode the characters rapidly (a single read can take less than 1/1,000th of a second), enabling high-speed automated processing.

Typical MICR data layout

From left to right, a typical MICR line contains:
– Routing (transit) number — a nine-digit code identifying the bank/branch
– Account number — identifies the payer’s account (length varies; example format in some systems uses up to 12 digits)
– Check number — indicates which check in a series (commonly shown as four digits)

Why MICR matters

• Automation: Standardized placement, ink, and fonts let clearinghouses and banks process millions of checks quickly and accurately.
• Fraud reduction: Magnetic ink and unique character shapes make photocopies and simple alterations easier to detect and more difficult to successfully counterfeit.
• Uniformity: The MICR standard enforces a consistent check layout required for machine readability.

Where MICR is used

Originally developed for checks in the late 1950s, MICR is also applied to other financial documents that benefit from machine-readable, tamper-resistant encoding, such as:
– Credit card invoices
– Rebate coupons
– Certain negotiable instruments and financial forms

Practical role in check clearing

Checks move through clearinghouses, banks, and central processing systems. Reader-sorter machines extract the MICR data to route funds and post transactions. A single check may be scanned multiple times across different institutions during the clearing process.

FAQ

• What is printed in magnetic ink?
  The routing number, account number, and check number are typically printed with magnetic ink in a standardized font.
• Why not just use visual printing?
  Magnetic ink enables automated, reliable machine reading even when the printed area is marked or damaged; it also adds a layer of security against counterfeiting.
• Are MICR fonts the same worldwide?
  No. E-13B predominates in North America, Australia, and the U.K., while CMC-7 is common in parts of Europe and South America.

Summary

MICR technology standardizes and secures the critical identifiers on checks—routing number, account number, and check number—by using magnetic ink and special fonts. This combination allows fast automated processing and helps reduce check fraud. Over decades, MICR has remained a core part of banking operations and has been adapted for other financial documents that need reliable, machine-readable security.