1099 Login
If you’ve ever looked at the bottom of a check and wondered what those numbers mean, or why they have to be printed with special ink, you’re not alone. MICR (Magnetic Ink Character Recognition) is one of the most durable standards in American banking. Understanding it matters if your organization prints, mails, or processes checks at any volume.
Here’s what MICR is, where it came from, and why it still matters today.
What Is MICR?
MICR is a technology used to print the characters at the bottom of checks and other financial documents using ink or toner containing iron oxide particles. Those iron oxide particles give the printed characters magnetic properties. This allows specialized banking equipment to read them accurately at high speed; even through stamps, signatures, or other markings on the check.
The characters can be read by both humans and machines. This was a deliberate design choice when the system was developed.
Where MICR Came From
The origins of MICR go back to a very practical problem: by the early 1950s, Bank of America (then the largest bank in the world) was overwhelmed with the sheer volume of paper checks. Manual check processing couldn’t keep pace with volume.
In 1950, Bank of America partnered with Stanford Research Institute (SRI) to develop an automated solution. The result was ERMA (Electronic Recording Machine, Accounting): a computing system that used magnetic ink to make checks machine-readable. In 1955, SRI demonstrated a prototype ERMA system to Bank of America. General Electric won the production contract, and delivered and installed the first production systems in 1959.
The American Bankers Association (ABA) formally established MICR as the standard for negotiable documents in 1958. By the end of 1959, the first checks printed with magnetic ink were in circulation. In 1963, the American National Standards Institute (ANSI) recognized the ABA’s standards as the American standard for MICR printing. The system has been maintained and updated as needed ever since.
The current governing standards are ANSI X9.100-20-2021 and ANSI X9.100-160-1-2021. They include the print specifications and placement/location requirements, respectively, maintained by the Accredited Standards Committee X9.
The Two MICR Fonts
There are two MICR fonts in use worldwide:
E-13B is used in the United States, Canada, the UK, Australia, and much of Asia and Central America. It contains the digits 0–9 and four special symbols: Transit, Amount, On-Us, and Dash. Each character is engineered to produce a distinctive magnetic waveform with at least two peaks and valleys. This lets machine readers distinguish characters reliably even at high processing speeds.
CMC-7 is used in France, Italy, Spain, Brazil, Mexico, and most other Spanish- and Portuguese-speaking countries. It was developed by the French computer company Machines Bull and adopted as the French standard in 1964. Each CMC-7 character produces a bar-code-style waveform with at least seven peaks and valleys.
If you’re printing checks for use in the United States, E-13B is the required font.
The MICR Line Printed at the Bottom of a Check
The row of numbers and symbols at the bottom of a check is called the MICR line. It contains four fields:
Routing/Transit Number — A 9-digit number that identifies the financial institution. The first digits encode the Federal Reserve district where the bank’s principal office is located. The ABA assigns and maintains routing numbers through its Routing Number Administrative Board. Each number is associated with a specific Federal Reserve district and territory.
Account Number — The customer’s bank account number (length varies by institution).
Check Number — The serial number of the check.
Amount — This field is blank when the check is printed. It’s added by the bank after the check is deposited. This process is called encoding.
On a standard personal check, these fields appear in order from left to right: Routing → Account → Check Number. The amount field is added at the far right after deposit. Business checks often use a different arrangement, with the check serial number appearing to the left of the routing number.
Magnetic Ink Is Required by Law
The Federal Reserve has stated clearly that industry standards have long required the MICR line to be printed in magnetic ink. Banks’ automated check-sorting equipment depends on being able to magnetize and read that line. Checks with non-magnetic ink in the MICR line can be classified as non-cash items, causing processing delays, errors, and potential fees.
Only the MICR line itself must be in magnetic ink. The rest of the check can be printed in standard ink.
Check 21 and Substitute Checks
The Check Clearing for the 21st Century Act (Check 21), effective October 28, 2004, modernized check processing by reducing legal barriers to check truncation. It introduced the substitute check as a legally equivalent instrument. A substitute check is a paper reproduction of an electronic image of an original check.
For a substitute check to be valid, it must bear a MICR line containing all of the information encoded on the original check’s MICR line and conform to industry standards for automated processing. Even in electronic check imaging, the MICR line is a legal and operational requirement.
MICR and Check Fraud
MICR’s magnetic properties make certain kinds of fraud harder to pull off, but check fraud remains a significant concern. The Office of the Comptroller of the Currency (OCC) identifies check washing — where criminals use chemicals to erase the ink from a legitimate check and rewrite the amount or payee — as one of the most common fraud methods. Importantly, check washing targets the handwritten or printed ink on the check body, not the MICR line itself.
A check missing a MICR line, or with MICR ink that appears shiny or raised rather than flat and dull, is a red flag for a potentially fraudulent instrument.
Positive Pay is a service where businesses send their bank a file of issued checks and the bank matches each presented check against that file. It is one of the most effective tools for catching MICR-related fraud before a payment clears.
What This Means If You’re Outsourcing Check Printing
For organizations that outsource check printing and mailing, MICR compliance isn’t something to take on faith. It requires MICR-certified toner or ink (containing iron oxide), proper paper stock, precise placement of the MICR line within the tolerances specified by ANSI X9.100-160, and quality control processes to verify signal strength and character readability on every check produced. It’s also worth confirming your vendor’s broader data security and compliance posture — since check runs typically involve the same sensitive account data covered by SOC 2, GLBA, and similar frameworks.
At Tab Service, we print on secure MICR check stock using bank-compliant processes and rigorous quality control, and generate Positive Pay files across more than 200 bank formats as part of every run. Every check that leaves our facility is both ready for automated MICR processing and matched to what your bank expects to see.
If you’re evaluating whether outsourced check printing makes sense for your organization, we’ve written a full breakdown of when outsourcing check printing and mailing pays off, including a checklist for evaluating a vendor.
Frequently Asked Questions
What does MICR stand for? MICR stands for Magnetic Ink Character Recognition, a technology that prints check characters using ink or toner containing iron oxide, giving them magnetic properties that banking equipment can read at high speed.
Is MICR ink legally required on checks? Yes. Industry standards have required magnetic ink on the MICR line since the 1950s, independent of the Check 21 Act. Checks without it can be delayed or rejected by automated bank processing.
What’s the difference between MICR ink and MICR toner? Both contain iron oxide particles for magnetic readability. MICR ink is typically used in inkjet printing and is more prone to smudging; MICR toner is used in laser printers and is the standard choice for higher-volume check production.
Does the whole check need to be printed in magnetic ink? No — only the MICR line itself needs magnetic ink. Everything else on the check (date, payee, amount, signature) can use standard ink.
What font is used for MICR in the United States? E-13B is the required font in the U.S., along with Canada, the UK, Australia, and most of Asia. CMC-7 is used instead across most of continental Europe and Latin America.
Sources: Federal Reserve (Regulation CC FAQ, 12 CFR Part 229), FDIC Consumer Compliance Examination Manual (March 2024), Office of the Comptroller of the Currency, American Bankers Association Routing Number Policy, ANSI X9 standards, SRI International, IEEE Annals of the History of Computing, Computer History Museum.
