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ISO 8583

The foundational financial transaction message standard used by ATMs, POS terminals, card switches, and payment gateways worldwide. Every card payment you make passes through this protocol.

Data Elements Reference

ISO 8583 defines up to 128 data elements (DEs). The table below covers the most commonly used fields across authorization, financial, and clearing messages. Private-use DEs (DE48, DE104-DE107) vary by network.

Core Transaction Fields

DE#NameFormatMax LenNotes
DE2Primary Account Numbern LLVAR19The cardholder's PAN. Masked in logs as first 6 + last 4.
DE3Processing Coden 666-digit code: 2 digits transaction type + 2 from account + 2 to account. E.g., 000000=purchase.
DE4Amount, Transactionn 1212Transaction amount in minor currency units (cents). Right-justified, zero-padded.
DE7Transmission Date & Timen 1010MMDDhhmmss format. Used for duplicate detection.
DE11Systems Trace Audit Numbern 66STAN — unique per transaction per day per terminal. Used to match request/response.
DE12Local Transaction Timen 66hhmmss at the terminal's local time.
DE13Local Transaction Daten 44MMDD at the terminal's local date.
DE14Expiration Daten 44YYMM format. Used in authorization validation.
DE18Merchant Typen 44MCC (Merchant Category Code) — ISO 18245. E.g., 5411=grocery stores.
DE22POS Entry Moden 33First 2 digits: how PAN was captured (01=manual, 05=chip, 07=contactless, 90=magnetic stripe). Last digit: PIN entry capability.
DE25POS Condition Coden 22Describes transaction conditions: 00=normal, 08=mail/phone, 59=ecommerce.

Terminal & Merchant Data

DE#NameFormatMax LenNotes
DE32Acquiring Institution IDn LLVAR11BIN of the acquiring bank. Identifies who submitted the transaction to the network.
DE35Track 2 Dataz LLVAR37Magnetic stripe track 2 data: PAN + separator + expiry + service code + discretionary data.
DE37Retrieval Reference Numberan 1212RRN — assigned by acquirer. Used to match transactions in dispute resolution.
DE38Authorization Codean 666-character code assigned by issuer on approval. Printed on receipts.
DE39Response Codean 2200=approved, 05=do not honor, 51=insufficient funds, 14=invalid card number. Critical field.
DE41Card Acceptor Terminal IDans 88Terminal ID assigned by acquirer. Identifies the physical or virtual terminal.
DE42Card Acceptor ID Codeans 1515Merchant ID (MID) assigned by acquirer. Links transactions to a merchant account.
DE43Card Acceptor Name/Locationans 4040Merchant name and location. Format: Name (25) + City (13) + Country (2).
DE49Currency Code, Transactionn 33ISO 4217 numeric currency code. E.g., 840=USD, 978=EUR, 826=GBP.

Security & EMV Fields

DE#NameFormatMax LenNotes
DE48Additional Data (Private)ans LLLVAR999Network-specific subelements. Used extensively by Visa and Mastercard for additional transaction context.
DE52Personal Identification Number Datab 88Encrypted PIN block (8 bytes). Format varies by PIN block format (ISO 0, 1, 3, 4).
DE55Integrated Circuit Card Datab LLLVAR255EMV chip data TLV structure. Contains ARQC, AIP, ATC, TVR, unpredictable number, and other chip-generated data.

Settlement & Network Fields

DE#NameFormatMax LenNotes
DE70Network Management Information Coden 33Used in 0800/0810 messages: 001=sign-on, 002=sign-off, 301=echo, 161=key exchange.
DE90Original Data Elementsn 4242Original MTI + STAN + date/time + acquiring ID. Required in reversal (0400) messages.
DE95Replacement Amountsn 4242Used in partial reversal to indicate the actual amounts after reversal.
DE102Account Identification 1ans LLVAR28From account identifier. Used in transfer and account-specific transactions.

Visa Private Use

DE#NameFormatNotes
DE104Transaction Descriptionans LLLVARVisa private use. Transaction narrative or additional descriptor.
DE105Credits, Numberans LLLVARVisa private use. Used in reconciliation messages.
DE106Credits, Reversal Numberans LLLVARVisa private use. Credit reversal count in reconciliation.
DE107Debits, Numberans LLLVARVisa private use. Debit count in reconciliation messages.