TLV Format Explained
TLV (Tag-Length-Value) is the foundational payload structure used in EMVCo QR payment systems. It defines how payment information is encoded, transmitted, parsed, and validated inside QR payloads.
What Is TLV Format?
TLV stands for Tag-Length-Value. It is a structured encoding format used in EMVCo QR specifications to organize payment-related information inside QR payloads.
Every payment element inside an EMV QR payload is represented using three components:
Tag
Identifies the type of payment data.
Length
Defines the size of the associated value.
Value
Contains the actual payment information.
Simple TLV Example
Consider the following simplified TLV structure:
5406100.00Represents transaction amount.
Value contains 6 characters.
Actual transaction amount.
EMV QR Payload Structure
EMVCo QR payloads combine multiple TLV blocks together to form a complete payment payload. Each block contains specific payment information such as merchant identifiers, transaction currency, amount, merchant category code, or CRC validation data.
00020101021126360014A000000677010111011300660000000005204581253033565802IN5910EMVQRHUB6007DELHI6304ABCDPayload Format Indicator
Defines EMV QR payload version.
Point of Initiation Method
Indicates static or dynamic QR type.
Merchant Category Code
Defines merchant business category.
Transaction Currency
Specifies currency code.
CRC Validation
Ensures payload integrity validation.
Why EMVCo Uses TLV Format
Structured Parsing
Payment systems can easily identify and parse payment fields.
Interoperability
Standardized payloads improve compatibility across payment ecosystems.
Flexible Payload Design
New tags and payment elements can be added without redesigning the structure.
Efficient QR Encoding
Compact TLV structures optimize QR payload sizes.
How QR Parsing Works
QR parsers decode TLV payloads sequentially. The parser reads the tag, identifies the length of the value, extracts the associated data, and moves to the next TLV block.
Scan
Read QR
Parse
Read TLV
Extract
Get values
Validate
Check CRC
CRC Validation in TLV Payloads
CRC (Cyclic Redundancy Check) validation helps verify payload integrity and ensures that the QR payload has not been corrupted or modified during transmission or scanning.
In EMVCo QR payloads, CRC validation is typically represented using Tag 63 and is calculated using standardized CRC algorithms.
CRC Validation Improves QR Reliability
Payment applications validate CRC values before processing payment transactions to reduce parsing errors and payload corruption risks.
Why Developers Should Understand TLV
QR Parser Development
TLV understanding is essential for building QR decoders and payment parsers.
Payment Integration
Fintech systems must correctly interpret EMVCo payload structures.
Merchant QR Generation
Payment generators construct QR payloads using TLV encoding.
Payload Validation
Validation engines use TLV parsing and CRC verification logic.