When a bank confirms an international wire, the receipt typically contains three or four different reference numbers. Customers often pick whichever looks longest and try to track with it — and end up on the wrong tracker. Here is the clean breakdown.
The UETR (Unique End-to-end Transaction Reference) is a 36-character UUIDv4 of the form 8-4-4-4-12 hexadecimal characters, like 174e3a04-c6a8-4d57-9d3e-9a1f2b4c5e6f. It lives in field 121 of an MT103 and is the only identifier that lets you track a payment end-to-end across the SWIFT GPI network.
The TRN (Transaction Reference Number) is bank-local. It is the reference your sending bank uses internally to identify the transaction in their core system. Banks use 8-16 character alphanumeric TRNs and they are useful only for chasing the payment within the originating bank, not across the network.
The ARN (Acquirer Reference Number) is a card-industry term — it has nothing to do with SWIFT wires. If a bank gives you an ARN for an international wire, they are using the term loosely, usually meaning the TRN.
Field 20 of an MT103 is the "Sender Reference" — typically an alphanumeric value the sending bank assigns and prints on the wire confirmation. It is reusable across banks but is not globally unique.
When you reach the Ohmyfin homepage and want to track, you need the UETR. If you only have a TRN or field 20 reference, ask your bank to convert it to the UETR — they can do this in seconds because the mapping is in their core banking system.
For pacs.008 (the ISO 20022 successor to MT103), the equivalent of the UETR is the UETR element inside the FIToFICstmrCdtTrf block. Same 36-character UUID, same purpose, just a different XML wrapper.
No. A UETR is exactly 36 characters with four hyphens. A 10-character reference is almost certainly a bank-local TRN or the field 20 sender reference.
No — Ohmyfin needs a UETR to query the SWIFT GPI network. The TRN is only visible inside your bank's core system.
Every MT103 sent since November 2018 carries a UETR. Older payments do not. Most banks added UETR support in 2018-2019 as part of the GPI mandatory rollout.
A UETR is a UUIDv4, which is 32 random hex characters split into 5 groups by hyphens. The first character can be any hex digit (0-9, a-f), so leading digits are perfectly normal.