The US doesn't use IBANs
If you're used to paying suppliers in Europe with an IBAN, paying a US supplier can initially feel like missing information — there's no single long code that contains everything. Instead, the US system is built around two separate numbers: a routing number and an account number, and depending on how the payment is being sent, you may also need a SWIFT/BIC code.
Routing numbers
A routing number is a 9-digit code that identifies the specific bank (and sometimes the specific branch or region) where an account is held. It's formally known as an ABA routing number, named after the American Bankers Association, which created the system back in 1910 — making it one of the oldest standardized banking identifiers still in active use today.
The 9 digits are structured as follows:
- The first four digits identify the Federal Reserve routing symbol.
- The next four digits identify the specific financial institution.
- The final digit is a check digit, calculated using a public checksum formula, which allows systems to catch many simple typos.
You'll typically find a routing number printed at the bottom left of a US check, or in a supplier's bank details / remittance instructions.
Account numbers
Unlike routing numbers, US account numbers have no fixed length or universal structure — they can range from about 4 to 17 digits depending on the bank. There's no embedded checksum the way there is with an IBAN, which means a single mistyped digit won't necessarily be caught automatically. This makes it especially important to double-check account numbers character by character when entering them, and ideally have the supplier confirm them back in writing.
Domestic routing number vs SWIFT/BIC — these are not interchangeable
This is one of the most common points of confusion when paying a US-based supplier from outside the US:
ABA routing number — used for domestic US payments, including ACH transfers (more on this below) and domestic wires within the US banking system.
SWIFT/BIC code — used for international wires into the US from abroad. Most US banks have their own SWIFT/BIC code, separate from their ABA routing number, and you'll need this — not the routing number — when initiating an international wire from outside the US.
Some larger US banks will provide both a routing number and a SWIFT/BIC code on their standard wire instructions specifically because international senders need the SWIFT/BIC while domestic systems use the routing number. If you've only been given a routing number by a US supplier and you're paying from abroad, it's worth asking directly whether they also have a SWIFT/BIC code for international wires, since not all routing numbers map cleanly to a usable SWIFT/BIC, and sending an international wire with only a domestic routing number can cause delays or rejected payments.
ACH vs wire — a quick note
Within the US, there are two common ways money moves between accounts, and they use the routing and account number differently in terms of speed and cost:
ACH (Automated Clearing House) — a batch-based domestic transfer system, typically used for routine payments. It's usually slower (often 1–3 business days) but significantly cheaper, sometimes free, which is why it's the default for most recurring domestic US payments.
Wire transfer — same-day or near-instant movement of funds, but typically carries a fee on both the sending and receiving side. Wires are the standard method for time-sensitive or larger payments, and the only practical option for most international transfers into a US account.
If you're paying a US supplier from abroad, you'll almost always be sending an international wire rather than an ACH payment, since ACH is a domestic-only network.
A quick word on Fedwire and CHIPS
For very large or time-critical domestic US payments, banks may use Fedwire (operated by the Federal Reserve) or CHIPS (a private real-time gross settlement system) rather than standard ACH. As an international payer, this distinction generally happens behind the scenes at the receiving bank — you don't need to specify which system to use, but it's worth knowing these exist if a supplier ever asks which network you'd like your wire to use.
Confirming details before you pay
Because the US account number has no built-in checksum, and because routing numbers can occasionally be mistaken for a SWIFT/BIC code (or vice versa) by someone unfamiliar with US banking, it's worth taking a moment before a first payment to a new US supplier to confirm: the routing number is the correct one for the type of payment you're making (domestic ACH/wire vs international wire), the account number has been provided and entered without transposed digits, and if you're paying internationally, you have a working SWIFT/BIC code rather than relying on the routing number alone.
Getting paid through correctly is just step one
Once the payment details are right, the next consideration for any USD invoice priced from abroad is timing — exchange rates move daily, and the difference between converting on a good day versus a bad one can be significant on a large invoice.
See how Easier FX tracks your USD invoices and flags the best time to convert →