What does the n in MT n99 mean?

It stands for the category digit. The free format message exists as MT199, MT299, MT399 and so on; the digit decides which team at the Receiver gets it.

Which category digit should I use for a free format message?

The one for the business the message is about: 1 for customer payments, 2 for interbank transfers, 3 for treasury, 5 for securities, 9 for cash management and accounts. That routes it to the unit able to act on it.

Are MT499 and MT799 the same as the other n99 messages?

No. The common n99 format does not apply in categories 4 and 7; the MT499 and MT799 are specified in the collections and trade finance guides.

What is the difference between MT n99 and MT n95?

The MT n95 is a structured query about a specific earlier message and expects an MT n96 answer. The MT n99 is free text for anything with no other message type. See MTn95.

What replaces the MT n99 in ISO 20022?

For payments, camt.110 and camt.111 for investigations, admi.024 for bilateral correspondence and pacs.002 for rejects. Free format messages in treasury, trade finance and securities stay on MT.

Common group, all categories

MT n99 Free Format Message (MT199 to MT999)

Written and maintained by ZagTrader. Last reviewed 21 October 2026. How this page is sourced and checked

MT n99 is the common group free format message: a reference, an optional related reference and up to 35 lines of text, for information that no other message type covers. The first digit routes it to the right team at the Receiver, from customer payments (MT199) to cash management (MT999). Categories 4 and 7 define their own free format messages, the MT499 and the MT799.

Message type: MTn99
Category: All (n = category digit)
Structure: 3 fields listed
ISO 20022: camt.110, camt.111, admi.024

Message types that use this layout

When MTn99 is used

The free format message is one of the common group messages that every category shares (see MTn92 for the group of n90 to n99). Financial institutions use it to send or receive information for which no other message type applies, and a corporate and its bank can use it the same way.

The only real choice is the category digit, which should route the message to the unit of the Receiver best able to act on it: 1 Category 1 customer payments and cheques (MT199); 2 Category 2 financial institution transfers (MT299); 3 Category 3 treasury markets, FX, money markets and derivatives (MT399); 4 Category 4 collections and cash letters (MT499, own layout); 5 Category 5 securities markets (MT599); 6 Category 6 precious metals, commodities and syndications (MT699); 7 Category 7 documentary credits and guarantees (MT799, own layout); 8 Category 8 travellers cheques (MT899); 9 Category 9 cash management and customer status (MT999).

The common n99 format does not apply in categories 4 and 7: the Swift standard refers to the category 4 and category 7 guides for the MT499 and MT799. The pages linked above cover the categories with the most traffic; this page covers the generic layout and the MT399, MT699 and MT899.

Use free text only when nothing structured fits. A question about a specific earlier message fits an MT n95 query (MTn95), which expects an MT n96 answer; a cancellation is an MT n92; and in treasury, a confirmation is amended with its own amendment function, not with an MT399. Because free text is read by people, quote the related reference in field 21 and name the deal or account in the first line of field 79.

A free format message informs; it never moves, blocks or confirms money, and it creates none of the obligations of a structured message. A copy of one outside the banking network is not authenticated.

MTn99 format: sequences and fields

Message text (block 4)Mandatory

Three fields, no sequences and no network validated rules across fields. Not used in categories 4 and 7.

Tag	Name	Status	Format	Meaning
20	Transaction Reference Number	M	16x	The Sender’s reference for this message. No leading or trailing slash and no double slash (T26).
21	Related Reference	O	16x	The reference of the message this one relates to, when there is one. Leave it out for a general notice.
79	Narrative	M	35*50x	The free text: up to 35 lines of 50 characters from the Swift x character set. In categories 1 and 2 a first line starting with /REJT/ or /RETN/ marks a payment reject or return and must follow the reject and return guidelines.

Format notation: n digits, a upper-case letters, c upper-case letters and digits, x any character of the Swift character set, d a decimal number with a comma, ! fixed length, [ ] optional, 4*35x up to 4 lines of 35 characters. M mandatory, O optional, C conditional (a rule decides).

Rules worth knowing

There are no network validated rules across fields for the MT n99; only the format of each field is checked.
Choose the category digit so that the message reaches the unit of the Receiver most capable of acting on it.
The n99 format is not used in categories 4 and 7; the MT499 and MT799 are defined in their own category guides.
In the MT199 and MT299, a field 79 starting with /REJT/ or /RETN/ must follow the payments reject and return guidelines (T80).
The network accepts a UETR in field 121 of the user header of the MT199, MT299 and MT999, so a message about a tracked payment can quote its UETR.
Some Swift services define structured versions of the MT199 and MT299 (for example gpi status confirmations, Stop and Recall and Case Management), identified by a service code in field 111 and validated against the service rules.

MTn99 example

ZagTrader Test Bank, Dubai (ZAGTAEADXXX), reorganises its treasury back office and tells its FX and money market counterparty BANKGB2LXXX, in an MT399, where queries about confirmations should go from November 2026. No structured message exists for this, and category 3 routes it to the counterparty’s treasury operations.

{1:F01ZAGTAEADAXXX0000000000}{2:I399BANKGB2LXXXXN}{4:
:20:ZT3992610210001
:79:WITH EFFECT FROM 261102 PLEASE SEND ALL QUERIES
ON FX AND MONEY MARKET CONFIRMATIONS AS MT395
TO ZAGTAEADXXX ATTN TREASURY OPERATIONS.
CONFIRMATION MATCHING AND OUR STANDARD
SETTLEMENT INSTRUCTIONS ARE UNCHANGED.
-}

Decode this example in the parser

Line by line

Line	What it says
{1:F01ZAGTAEADAXXX0000000000}{2:I399BANKGB2LXXXXN}{4:	Sender ZAGTAEADXXX, input MT399 to BANKGB2LXXX: category 3, treasury markets.
:20:ZT3992610210001	ZagTrader’s reference. No field 21: the notice relates to no earlier message.
:79:WITH EFFECT FROM 261102 PLEASE SEND ALL QUERIES	Free text, at most 50 characters per line.
ON FX AND MONEY MARKET CONFIRMATIONS AS MT395
TO ZAGTAEADXXX ATTN TREASURY OPERATIONS.
CONFIRMATION MATCHING AND OUR STANDARD
SETTLEMENT INSTRUCTIONS ARE UNCHANGED.	Says what does not change, so the Receiver does not update its static data by mistake.
-}	End of block 4.

An MT699 or MT899 has exactly the same fields; only the category digit changes.

BICs and references are made up.

Common errors and rejects

Line longer than 50 characters or more than 35 lines
Field 79 is limited to 35 lines of 50 characters. Wrap the text before sending; longer content needs several messages.
Characters outside the Swift x set
Characters such as @, &, #, % and accented letters are not allowed. Write them out (AT, AND) or the message is rejected.
MT n99 sent in category 4 or 7 with the generic layout
Collections and trade finance use their own free format messages, the MT499 and MT799, as defined in their category guides. Check the category 4 or 7 specification before building one.
Free text used where a structured message exists
Cancellations (MT n92), queries about a specific message (MT n95), confirmations and amendments have their own messages. Receivers often do not act on free text that tries to replace them.
Wrong category digit
An MT199 about an FX deal lands with the payments team, an MT399 about a customer payment with treasury. Pick the category of the business the message is about.

MTn99 in ISO 20022

There is no one-to-one ISO 20022 equivalent of a free format message. For payments, Clearstream’s adoption schedule maps MT n99 used for enquiries and investigations to camt.110 Investigation Request and camt.111 Investigation Response, and bilateral MT199 and MT299 correspondence to admi.024 Notification of Correspondence. Payment rejects reported by MT199 or MT299 become a pacs.002.

According to J.P. Morgan, Swift deferred the enquiry and investigation changes from November 2026 to a partial release planned for Q1 2027. Treasury (category 3), collections (category 4), trade finance (category 7) and securities (category 5) messages were not part of the CBPR+ migration, and their free format messages remain in use on FIN.

MTn99 questions

What does the n in MT n99 mean?: It stands for the category digit. The free format message exists as MT199, MT299, MT399 and so on; the digit decides which team at the Receiver gets it.
Which category digit should I use for a free format message?: The one for the business the message is about: 1 for customer payments, 2 for interbank transfers, 3 for treasury, 5 for securities, 9 for cash management and accounts. That routes it to the unit able to act on it.
Are MT499 and MT799 the same as the other n99 messages?: No. The common n99 format does not apply in categories 4 and 7; the MT499 and MT799 are specified in the collections and trade finance guides.
What is the difference between MT n99 and MT n95?: The MT n95 is a structured query about a specific earlier message and expects an MT n96 answer. The MT n99 is free text for anything with no other message type. See MTn95.
What replaces the MT n99 in ISO 20022?: For payments, camt.110 and camt.111 for investigations, admi.024 for bilateral correspondence and pacs.002 for rejects. Free format messages in treasury, trade finance and securities stay on MT.

All MT messages · ISO 20022 messages · Codes · Troubleshooting