MT799 Free Format Message (Trade Finance)

When MT799 is used

Every Swift category has a free format message ending in 99: the MT199 for customer payments, the MT299 for bank transfers, the MT599 for securities, and the MT799 for documentary credits and guarantees. The category digit routes the message to the department of the receiving bank that can act on it, so an MT799 lands with the trade finance team.

Banks use the MT799 for trade correspondence that has no message of its own: chasing documents sent under a credit, asking for courier details, telling a correspondent that a guarantee or credit is about to be issued, or agreeing details before a structured message is sent. Swift’s category 7 guide also points to the MT799 when a reimbursing bank must warn the issuing bank of a future debit.

Swift’s category 7 guide defines the MT799 as a message financial institutions use to send or receive information. The Sender and the Receiver are the network addresses (BICs) in the header blocks, and category 7 messages are signed, which needs an RMA authorisation between the two banks. A private person has no address on the network and cannot send an MT799; a customer can only ask its bank to send one.

Because it is free text, an MT799 creates no obligation of the kind a structured message does. A credit is issued with an MT700, a guarantee or standby letter of credit with an MT760, and money moves in payment messages. An MT799 can say that a bank intends to do something, but it does not move or block money.

Since Swift’s overhaul of category 7 (standards releases 2018 to 2021) there is also the MT759 Ancillary Trade Structured Message, with a coded function (for example a financing request or a fraud alert) about an existing credit or guarantee. Swift recommends the MT759 over the MT799 where it fits, but the MT799 remains available and widely used.

MT799 format: sequences and fields

Rules worth knowing

• Use a structured message when one exists. A credit is issued with MT700, amended with MT707, and a guarantee issued with MT760. Text in an MT799 that tries to do the same has none of the meaning those messages carry.
• Field 79 uses the x character set. An e-mail address or an ampersand in a company name has to be written out (for example AT and AND).
• Quote the credit or guarantee number in field 21 and again in the first line of field 79, so the message can be matched to its file without opening it.
• An MT799 is authenticated on the network between the two banks. A copy of it on paper, in a PDF or in an e-mail is not authenticated: only the receiving bank can confirm that it really received the message.

MT799 example

ZagTrader Test Bank in Dubai (ZAGTAEADXXX) issued documentary credit ZTLC2610200001 to BANKGB2LXXX in London. BANKGB2LXXX paid the beneficiary and sent an MT754 saying the documents were on their way by courier, under its reference BGL7541026001. A week later the documents have still not arrived in Dubai, so the issuing bank asks for the courier details in an MT799.

{1:F01ZAGTAEADAXXX0000000000}{2:I799BANKGB2LXXXXN}{4:
:20:ZT799261103001
:21:BGL7541026001
:79:RE OUR DOCUMENTARY CREDIT NO. ZTLC2610200001
FOR USD 250000,00 IN FAVOUR OF ACME COMPONENTS LTD
WE REFER TO YOUR MT754 DATED 26 OCT 2026.
THE DOCUMENTS HAVE NOT YET REACHED OUR COUNTERS.
PLEASE ADVISE BY RETURN THE NAME OF THE COURIER,
THE AIR WAYBILL NUMBER AND THE DISPATCH DATE.
REGARDS
TRADE OPERATIONS
-}

Line by line

The BICs, names and references are made up.

Each line of field 79 stays within 50 characters and uses only characters from the x set.

Common errors and rejects

1. Reference with a leading, trailing or double slash (T26)

   Fields 20 and 21 must not start or end with a slash or contain //. Credit numbers copied from another system sometimes carry slashes; replace them before sending.

2. Text too long or with invalid characters

   Field 79 holds 35 lines of 50 characters in the x character set. Long letters pasted from a word processor break both limits: lines are too long and characters such as @, &, % or curly quotes are rejected. Wrap the text and replace the characters.

3. Free text used instead of a structured message

   An amendment, an authorisation to pay or a guarantee sent as an MT799 is not processed as one: the receiving bank may treat it as information only or ask for the proper message. Use MT707 for amendments, MT760 for guarantees and MT759 for coded requests about an existing credit or guarantee.

4. No related reference

   An MT799 without field 21 and without the credit number in the text goes to a manual queue at the receiving bank while someone works out which file it belongs to. Always quote the credit or guarantee number.

5. An MT799 "proof of funds" offered by a third party

   If a broker, a lender or an investment promoter offers to "send an MT799" or asks you to arrange one before they release funds, treat it as a warning sign, not a step in a real deal. The FBI lists claims of "blocked funds" or "proof of funds" with an MT799 or MT760, together with advance fees and returns out of proportion to the risk, as common signs of fraud. Ask your own bank to verify any claimed message directly with the bank that is said to have sent it.

ISO 20022

There is no ISO 20022 page for the MT799 because it has no ISO 20022 replacement in use for trade finance. Swift ended the MT/MX coexistence period on 22 November 2025 for cross-border payment instructions; category 7 trade messages, including the MT799, were not part of that deadline and are still exchanged as MT.

Inside category 7 the structured alternative is the MT759, which carries a coded function and the reference of the credit or guarantee. ISO 20022 trade messages (tsrv for guarantees and standbys, tsin for trade initiation and invoice financing, tsmt for trade data matching) do not include a free format message that replaces the MT799.

The payments free format MT199 is in a different position: it sits next to payment instructions that are now ISO 20022 (pacs.008). See its page for what that means for payment queries.

Related messages

• MT700Issue of a Documentary Credit
• MT199Free Format Message
• MT103Single Customer Credit Transfer
• MT202General Financial Institution Transfer

MT799 questions

What is an MT799?

It is the free format message of Swift category 7 (documentary credits and guarantees). One bank uses it to send another bank free text about trade business when no structured message fits, for example a question about documents sent under a letter of credit.

Is an MT799 proof of funds or a bank guarantee?

No. An MT799 is free text between two banks. It does not block, reserve or move money and does not create a guarantee. A guarantee or standby letter of credit is issued with an MT760, and money moves in payment messages. The FBI warns that "proof of funds" or "blocked funds" claims built on an MT799 or MT760 are a common feature of investment fraud.

Can a company or a person send an MT799?

A private person cannot. The category 7 standard defines the MT799 as a message between financial institutions on the Swift network, and category 7 messages need an RMA authorisation between the sending and receiving bank. A customer can only ask its bank to send one, and the bank decides whether the request makes sense.

What is the difference between MT799 and MT760?

The MT760 issues a guarantee or a standby letter of credit: a binding undertaking by the issuing bank. The MT799 is free text. Banks sometimes send an MT799 before an MT760 to say that a guarantee is coming, but only the MT760 is the guarantee.

What is the difference between MT799 and MT199?

Both are free format messages with the same three fields. The category digit decides where the message goes: an MT199 goes to the payments team and is about customer payments, an MT799 goes to the trade finance team and is about credits and guarantees.

How do I check whether an MT799 is genuine?

Ask your own bank to confirm it with the bank named as the Sender, through the banks’ own channels. A screenshot, PDF or printed copy proves nothing, because anyone can type a message in MT799 layout. A real MT799 exists only between the two banks on the network.