Field 25 in SWIFT Messages: Format, Examples and How to Use It

Field 25 in a SWIFT message is the Account Identification field. It identifies the account the message relates to — most commonly the account holder’s account in an MT940 statement message, or the debited/credited account in MT900/MT910 confirmations. Field 25 carries up to 35 alphanumeric characters and is one of the most frequently misformatted fields in correspondent banking. Two main format options exist: :25: (account number only) and :25P: (account identification with BIC, used when the receiver is not the account owner).

What is Field 25 in a SWIFT message?

Field 25 is the Account Identification field used in SWIFT messages, defined in the SWIFT Standards under Category 9 (Cash Management and Customer Status). Its purpose is to identify the account that a message relates to — the account being credited, debited, or reported on, depending on the message type.

Field 25 is widely searched as “tag 25” — both terms are used interchangeably. “Tag” is the term most commonly used by developers reading raw SWIFT messages; “Field” is the term used in SWIFT’s own specifications. They refer to the same thing.

Where Field 25 appears most often:

• MT940 (Customer Statement Message) — identifies the account the statement relates to
• MT942 (Interim Transaction Report) — same purpose as MT940 for intra-day statements
• MT900 (Confirmation of Debit) — identifies the debited account
• MT910 (Confirmation of Credit) — identifies the credited account
• MT950 (Statement Message) — bank-to-bank account statement

Note that Field 25 is not a standard mandatory field in MT103 (Single Customer Credit Transfer) messages. MT103 uses Field 50 (Ordering Customer) and Field 59 (Beneficiary Customer) to identify the parties to a payment. Field 25 references in payment workflows usually relate to the corresponding MT940/MT942 confirmations rather than the MT103 itself.

Field 25 format and structure

Field 25 has two main format options, both denoted in the SWIFT specifications as 25a where “a” indicates the option used. The two are:

Key format rules:

• Maximum length: 35 characters for the account portion
• Character set: Alphanumeric (SWIFT character set X)
• Leading slash: The account value is typically preceded by a forward slash (/) when included in payment messages
• Branch prefix: For non-IBAN accounts sent via channels other than SWIFTNet FIN, the Bank Identification Code may be prefixed before the account number, separated by a forward slash
• BIC validation (Option P only): The BIC must be a registered Business Identifier Code. Invalid BICs trigger SWIFT validation errors T27, T28, T29, or T45

Field 25 in MT940 (Customer Statement Messages)

The most common use of Field 25 — and the highest-volume query for this topic — is in MT940 Customer Statement messages. An MT940 is the SWIFT-format end-of-day account statement, used by banks to report account activity to corporate customers and other financial institutions.

In an MT940, Field 25:

• Identifies the account the statement relates to
• Appears exactly once per account/statement date combination
• Is a mandatory field — an MT940 without a valid Field 25 will fail validation
• Can carry either a domestic account number, an IBAN, or a BIC-prefixed account depending on the originating bank’s configuration

MT940 example showing Field 25

:20:2131200000013576
:25:006000117654321
:28C:38
:60F:C230101CAD15500,00
:61:2301011231D150,50NTRF1010-1//91023487656-2
:86://50//006000117654321
:62F:C230131CAD15349,50

In this example, :25:006000117654321 identifies the customer’s account that the statement applies to. The bank then lists each transaction (Field 61) and the opening and closing balances (Fields 60F and 62F) for that account.

Field 25 in MT900 and MT910 (Debit and Credit Confirmations)

In MT900 (Confirmation of Debit) and MT910 (Confirmation of Credit) messages, Field 25 identifies the account that has been debited or credited:

• MT900: Field 25 identifies the account which has been debited, and optionally the identifier code of the account owner
• MT910: Field 25 identifies the account which has been credited, and optionally the identifier code of the account owner

In both cases, Option P (:25P:) is the variant used when the receiver of the message is not the account owner — for example, when a correspondent bank is notifying a third party about activity on an account it manages on behalf of someone else. When the receiver is the account owner, Option A (:25:) suffices.

MT910 example with Option P

:20:CREDIT123456
:21:RELATED789012
:25P:/006000117654321
BANKGB22XXX
:32A:230415USD50000,00
:50K:/9876543210
ABC TRADING LIMITED
LONDON

Here, Field 25P carries the credited account number followed by the BIC of the account owner — used because the receiver of this MT910 confirmation is a third party rather than the account holder.

Field 25 vs related SWIFT fields

Field 25 is one of a family of party-identification and account-identification fields used across SWIFT messages. The most commonly confused with Field 25:

The simplest distinction: Field 25 identifies an account, while Fields 50, 52, 56, 57, 58, and 59 identify parties. A SWIFT message can carry both — for example, an MT940 statement showing activity for Field 25 account, with each Field 61 line referencing the parties that triggered each transaction.

Common Field 25 errors and how to fix them

Field 25 best practices

• Validate before transmission. Most SWIFT validation errors caught at the receiving bank could have been caught at the sending bank with proper field-level checks
• Choose the right option (A vs P). Default to :25: unless your messaging architecture requires the receiver to be distinct from the account owner
• Use IBANs where possible. They include built-in check digits and reduce account-identification errors significantly
• Maintain an audit trail. Log Field 25 contents alongside the message reference (Field 20) for reconciliation and compliance review
• Document branch-prefix conventions. If your bank prefixes non-IBAN accounts with the BIC or domestic branch code, ensure this is consistent and documented for downstream parsing
• Test against ISO 20022 mappings. SWIFT MT to MX migration is ongoing under the ISO 20022 programme; Field 25 maps to specific elements in the equivalent MX messages, and edge cases (long accounts, Option P) frequently surface during conversion

Developer integration tips

For teams integrating SWIFT MT messages into core banking, treasury management, or reconciliation systems:

• Parse the option suffix. Treat :25: and :25P: as distinct field instances with different structure — Option P parsing must extract both the account string and the BIC on the second line
• Build automated validation. Check length (≤35 chars), character set (SWIFT X), presence (mandatory in MT940/942/950/900/910), and BIC validity for Option P before passing the message downstream
• Handle leading slash consistently. The forward slash before the account number is convention, not always present. Parsers should accept both /006000117654321 and 006000117654321
• Map to ISO 20022. In the ISO 20022 equivalents (camt.052 for intra-day, camt.053 for end-of-day), Field 25 maps to the <Acct> element with <Id> containing the IBAN or domestic account identifier
• Log error codes specifically. SWIFT validation errors related to Field 25 typically appear with codes in the T2x range (BIC validation), C24 (option misuse), and D-series (field length)

Frequently asked questions

What is Field 25 in a SWIFT message?

Field 25 is the Account Identification field in SWIFT messages. It identifies the account the message relates to — most commonly in MT940 customer statement messages, where it shows which account the statement applies to. Field 25 carries up to 35 alphanumeric characters and is mandatory in statement and confirmation message types.

What is Tag 25 in MT940?

Tag 25 in MT940 identifies the account the statement relates to. There is one Tag 25 per account per statement date. It typically contains either a domestic account number, an IBAN, or a BIC-prefixed account, depending on the originating bank’s setup. Tag 25 is mandatory in MT940 — an MT940 without it will fail SWIFT validation.

What is the difference between Field 25 and Field 25P?

Field 25 (Option A) contains only the account number. Field 25P (Option P) contains the account number plus the BIC of the account owner. Option P is used only when the receiver of the message is not the account owner — typically in MT900 debit confirmations and MT910 credit confirmations sent to third parties.

Is Field 25 used in MT103?

Field 25 is not a standard mandatory field in MT103 Single Customer Credit Transfer messages. MT103 identifies parties using Field 50 (Ordering Customer) and Field 59 (Beneficiary Customer). Field 25 references in MT103 workflows usually relate to associated MT940 or MT900/MT910 confirmation messages, not the MT103 itself.

What is the maximum length of Field 25?

Field 25 carries up to 35 alphanumeric characters in the account portion. For Option P (Field 25P), an additional BIC of 8 or 11 characters follows on a separate line. Both must conform to SWIFT character set X (alphanumeric only).

Why does my MT940 have only one Tag 25?

MT940 specifications require exactly one Tag 25 per account/statement date combination. If a customer has multiple accounts, each generates a separate MT940 message — they are not combined into one statement with multiple Tag 25 occurrences. A single MT940 always reports on a single account.

What characters are allowed in Field 25?

Field 25 follows SWIFT character set X, which permits alphanumeric characters only — letters A–Z, digits 0–9, and a small set of punctuation including forward slash, hyphen, comma, full stop, and a few others. Spaces and most special characters are not permitted. Most errors arise from copying account references that include disallowed punctuation.

How does Field 25 map to ISO 20022?

In ISO 20022 messages (camt.052 for intra-day reports, camt.053 for end-of-day statements), Field 25 maps to the <Acct> element containing an <Id> child with either an IBAN or a domestic account identifier. The migration from MT to MX messaging under the SWIFT ISO 20022 programme is ongoing, and Field 25 edge cases (long account strings, Option P with BIC) often surface during conversion testing.

Related guides

• Free SWIFT code checker — verify any BIC/SWIFT code
• MT103: what you need to know — the customer credit transfer message explained
• MT202 vs MT202 COV — bank-to-bank transfer messages
• Clearing codes explained — sort codes, BIC, SWIFT, IBAN and more

Speak to a specialist

If you’ve encountered Field 25 errors on an international transfer, or you’re handling a large payment where account identification accuracy matters, Cambridge Currencies can help. We work with FCA-authorised partners Currencycloud (FRN 900199) and ScioPay (FRN 927951), and every transfer is verified by phone with a named specialist before settlement. Request a quote to discuss your transfer.