9F66
Terminal Transaction QualifiersA 4-byte terminal-supplied field, defined by the Visa contactless kernel (Kernel 3), that tells the card which transaction paths and capabilities the reader supports: mag-stripe vs EMV mode, online PIN, signature, offline data authentication for online authorizations, whether an online cryptogram or CVM is required, and consumer-device CVM. The card reads it to choose its processing path.
Tag 9F66 is the reader introducing itself. Before the card decides how to run a contactless transaction, it needs to know what the terminal on the other side is capable of and what it will insist on — and the Terminal Transaction Qualifiers is how the terminal says so. Four bytes, sent to the card as part of the GET PROCESSING OPTIONS data built from the PDOL. It is defined by the Visa contactless kernel, Kernel 3, which is the single most important thing to know about it.
Byte 1 covers the paths the reader supports: mag-stripe mode, EMV mode, EMV contact chip, offline-only operation, online PIN, signature, and offline data authentication for online authorizations. Byte 2 is where the reader states its demands rather than its abilities — online cryptogram required, CVM required — plus offline PIN support for contact chip. Byte 3 carries issuer update processing and consumer device CVM, the bit that matters for phone and watch wallets. Byte 4 is reserved in full.
The distinction between bytes 1 and 2 is the one to hold on to. Byte 1 is "here is what I can do"; byte 2 is "here is what I will require regardless". A reader can support a dozen paths and still force every transaction online by setting the online-cryptogram-required bit, which is precisely how a terminal that appears to support offline transactions ends up going online every single time. If that is your symptom, decode byte 2 before anything else.
TTQ also does not travel alone. The terminal sends 9F66; the card answers with its own qualifiers in 9F6C, the Card Transaction Qualifiers. Reading one without the other gives you half a negotiation — the terminal declares, the card responds, and the transaction path is what the two of them agree on. The value 36000000 is a realistic starting point: EMV mode supported, EMV contact chip supported, online PIN supported and signature supported, with no requirements asserted in byte 2 at all.
One caution before you trust any 9F66 decoder, including this one: 9F66 belongs to Kernel 3. Other kernels and other brands use their own terminal-qualifier elements with their own layouts, and the same four bytes decoded against the wrong kernel will produce a plausible, confident, wrong answer. Establish the kernel first, then decode.
Properties
| Tag | 9F66 |
|---|---|
| Name | Terminal Transaction Qualifiers |
| Format | Binary |
| Length | 4 bytes |
| Source | Terminal |
| Templates | — |
| Books | Book C-3 |
Bit-by-bit breakdown
| Byte | Bit | Meaning |
|---|---|---|
| 1 | 8 | Mag-stripe mode supported |
| 1 | 7 | RFU (Reserved for Future Use) RFU |
| 1 | 6 | EMV mode supported |
| 1 | 5 | EMV contact chip supported |
| 1 | 4 | Offline-only reader |
| 1 | 3 | Online PIN supported |
| 1 | 2 | Signature supported |
| 1 | 1 | Offline Data Authentication for Online Authorizations supported |
| 2 | 8 | Online cryptogram required |
| 2 | 7 | CVM required |
| 2 | 6 | (Contact Chip) Offline PIN supported |
| 2 | 5 | RFU (Reserved for Future Use) RFU |
| 2 | 4 | RFU (Reserved for Future Use) RFU |
| 2 | 3 | RFU (Reserved for Future Use) RFU |
| 2 | 2 | RFU (Reserved for Future Use) RFU |
| 2 | 1 | RFU (Reserved for Future Use) RFU |
| 3 | 8 | Issuer Update Processing supported |
| 3 | 7 | Consumer Device CVM (CDCVM) supported |
| 3 | 6 | RFU (Reserved for Future Use) RFU |
| 3 | 5 | RFU (Reserved for Future Use) RFU |
| 3 | 4 | RFU (Reserved for Future Use) RFU |
| 3 | 3 | RFU (Reserved for Future Use) RFU |
| 3 | 2 | RFU (Reserved for Future Use) RFU |
| 3 | 1 | RFU (Reserved for Future Use) RFU |
| 4 | 8 | RFU (Reserved for Future Use) RFU |
| 4 | 7 | RFU (Reserved for Future Use) RFU |
| 4 | 6 | RFU (Reserved for Future Use) RFU |
| 4 | 5 | RFU (Reserved for Future Use) RFU |
| 4 | 4 | RFU (Reserved for Future Use) RFU |
| 4 | 3 | RFU (Reserved for Future Use) RFU |
| 4 | 2 | RFU (Reserved for Future Use) RFU |
| 4 | 1 | RFU (Reserved for Future Use) RFU |
Decoded example
Example value: 36000000
- B1·b6EMV mode supported
- B1·b5EMV contact chip supported
- B1·b3Online PIN supported
- B1·b2Signature supported
Interactive decoder
Paste a hex value for this tag to decode it in your browser. Nothing is sent anywhere.
- B1·b6EMV mode supported
- B1·b5EMV contact chip supported
- B1·b3Online PIN supported
- B1·b2Signature supported
Frequently asked questions
- What is EMV tag 9F66?
- Tag 9F66 is the Terminal Transaction Qualifiers (TTQ), a 4-byte field the terminal sends to the card during a contactless transaction, as part of the GET PROCESSING OPTIONS data built from the PDOL. It tells the card which transaction paths the reader supports (mag-stripe or EMV mode, online PIN, signature, CDCVM) and which conditions it requires, such as an online cryptogram or cardholder verification.
- What does TTQ mean in EMV?
- TTQ stands for Terminal Transaction Qualifiers. It is defined by the Visa contactless kernel (Kernel 3) and is the terminal declaring its capabilities and its requirements so the card can choose its processing path. Byte 1 states what the reader can do; byte 2 states what it will require regardless.
- How do I decode a TTQ value like 36000000?
- 36000000 sets four bits in byte 1: EMV mode supported, EMV contact chip supported, online PIN supported and signature supported. Bytes 2 to 4 are all zero, so the reader asserts no requirements. Paste your own 4-byte value into the decoder on this page to resolve each bit against the Kernel 3 layout.
- What is the difference between TTQ (9F66) and CTQ (9F6C)?
- The TTQ is sent by the terminal to the card and states what the reader supports and requires. The CTQ (Card Transaction Qualifiers, tag 9F6C) is returned by the card and states its side of the same negotiation. The transaction path is the result of both, so they are normally read together.
- Does 9F66 work the same on every card brand?
- No. 9F66 is defined by the Visa contactless kernel (Book C-3, Kernel 3). Other kernels and brands use different terminal-qualifier elements with different bit layouts, so the kernel must be established before the value is decoded — decoding against the wrong kernel yields a wrong answer that still looks valid.
Sources
- EMV Contactless Book C-3 (Kernel 3), Annex A.2 (Terminal Transaction Qualifiers) (page pending verification)
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