Routing Transit Number (RTN)

A routing transit number (RTN) is a nine-digit code that identifies a U.S. bank or financial institution for the purpose of processing electronic funds transfers and clearing checks. Often called a routing number, transit number, or ABA number, it ensures transactions are routed to the correct bank.

How an RTN is structured

• Length: 9 digits.
• First four digits: designate the Federal Reserve district or processing center.
• Next four digits: identify the specific bank or institution.
• Last digit: a checksum/classifier used for validation.
• On a paper check, the RTN appears as the left-most nine digits on the bottom line. A fractional routing symbol (a smaller fraction near the top of some checks) provides a legacy alternate form.

Routing numbers always begin with 0, 1, 2, or 3.

Primary uses

• ACH transfers (e.g., payroll direct deposit, bill payments)
• Domestic wire transfers
• Check clearing and processing
• Setting up electronic payment relationships (employer direct deposit, automatic payments)

Using the correct routing number is essential: an incorrect RTN can cause delays, failed transfers, or misdirected funds.

Where to find your routing number

• Bottom left of a paper check (left-most nine digits).
• Bank’s website or online banking portal (often listed with account details).
• Bank customer service or account statements.

Note: Some banks use different routing numbers for ACH, wire transfers, or paper transactions — verify the correct routing number for the transaction type.

Routing numbers vs. international bank identifiers

• RTN: for domestic U.S. transactions only.
• SWIFT/BIC: used for international bank-to-bank transfers.
• IBAN: used in many countries to identify account and branch details for international transfers (not used in the U.S.).

For international transfers, you’ll typically need a SWIFT code and the recipient’s account information rather than a U.S. RTN.

Important considerations

• Multiple routing numbers: A single bank may maintain separate routing numbers for ACH, wires, and checks. Always confirm which to use.
• Security: Routing numbers are not secret (they appear on checks), but pairing them with accurate account numbers is critical to keep funds secure.
• Assignment and registry: Routing numbers are administered through industry processes and registries; new financial institutions apply for and receive assigned numbers.
• Errors: Double-check both routing and account numbers before initiating transfers to avoid delays or lost funds.

Quick FAQs

• What is the RTN on a check? The nine digits at the bottom-left.
• Is an RTN required for direct deposit? Yes; employers typically require both your RTN and account number.
• Can one bank have multiple routing numbers? Yes — often by transaction type or region.
• Do routing numbers work internationally? No — use SWIFT/IBAN for international transfers.

Key takeaways

• An RTN is a nine-digit identifier for U.S. banks used in domestic electronic transfers and check processing.
• It appears as the first nine digits on the bottom-left of a check and is usually available in online banking.
• Use the correct routing number for the specific transaction type (ACH, wire, or paper) to ensure smooth processing.