MT799 SWIFT format: the fields and how to read one
By the Vanguard Verify desk · Published 2026-10-26 · Updated 2026-10-26
Short answer: an MT799 is a SWIFT Category 7 free-format message with only three fields. Field 20 is the transaction reference (mandatory), field 21 is the related reference (optional) and field 79 is the narrative (mandatory, up to 35 lines of 50 characters). Banks send it to each other over the SWIFT network. It is not a payment, a guarantee or a binding commitment unless its text and the banks' agreements make it one.
MT799 field structure
| Tag | Field name | Status | Format |
|---|---|---|---|
| 20 | Transaction Reference Number | Mandatory | 16x (up to 16 characters) |
| 21 | Related Reference | Optional | 16x |
| 79 | Narrative | Mandatory | 35*50x (up to 35 lines of 50 characters) |
The sender and receiver are identified by their BIC codes in the message header, not in the body. Only SWIFT-connected institutions can send or receive the message. For what the message is used for, see MT799 meaning.
How to check an MT799 claim
- Ask which bank received it. An MT799 goes bank to bank, so your own bank (or the counterparty's bank) is the only party that can confirm it arrived.
- Check both BICs. Look up the sending and receiving BIC codes and confirm they belong to the banks named. See how to verify a SWIFT BIC code.
- Have your bank's trade or correspondent desk confirm receipt. Do this through the bank's official channels, not through phone numbers or emails on the document you were sent.
- Read field 79 carefully. Most MT799s say something non-binding, such as "we confirm our client has sufficient funds" or "we are ready to issue". These are not commitments to pay.
- Match the references. The field 20 reference should match what the sending bank confirms.
Red flags
- You get a PDF, a screenshot or a Word file labelled "MT799". A screenshot is not proof that a SWIFT message was ever sent.
- The narrative uses words like "irrevocable", "guaranteed" or "blocked funds" with no reference to an underlying instrument such as an MT760 or MT700.
- You are asked to pay a fee to receive an MT799, or the sender wants to send one from a "leased" account.
- The sending BIC does not match the bank named in the text, or the bank does not use SWIFT at all.
- The field lengths are impossible, for example a field 20 longer than 16 characters.
MT799 vs other Category 7 messages
A documentary credit is issued by MT700, and guarantees and standby letters of credit by MT760. MT799 is only a free-format note between banks. It can come before or after these instruments but cannot replace them. Compare MT760 vs MT799.
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FAQ
How many fields does an MT799 have?
Three: field 20 (transaction reference, mandatory), field 21 (related reference, optional) and field 79 (narrative, mandatory).
How long can the MT799 narrative be?
Field 79 allows up to 35 lines of up to 50 characters each.
Is an MT799 a guarantee?
No. It is a free-format message. A guarantee or standby letter of credit is normally issued by MT760.
Can I verify an MT799 from a PDF?
No. Only the receiving bank can confirm, through its official channels, that the SWIFT message arrived.
Vanguard Verify is run by Vanguard Trade Capital Goods Wholesalers DWC-LLC, Dubai South, Licence 14282. This answer is general information, not legal or financial advice.