NFC-B Explained: The Other Half of ISO 14443
NFC-A gets all the attention because it's what's in your NTAG stickers and MIFARE cards. But ISO 14443 defines a second, incompatible standard — NFC-B — that shows up in payment cards, transit passes, and some national ID programs. Here's what actually differs between the two, where each one turns up in the real world, and what it means the next time NFCore tells you which type a card is.
What it is (one-paragraph answer)
NFC-B is the ISO/IEC 14443 Type B standard — one of two incompatible physical-layer specifications that contactless cards and NFC tags are built on, the other being Type A (NFC-A). Both run at the same 13.56 MHz frequency and 106 kbit/s speed. They just encode bits differently, so a Type A-only reader can't talk to a Type B card. If you've read our breakdown of ICODE and ISO 15693, you already know ISO has more than one contactless family under its umbrella. NFC-B is the one you're most likely carrying in your wallet right now without realizing it.
How it actually works
Modulation and coding: what actually differs from Type A
The difference between Type A and Type B isn't speed or range. It's how each side encodes its bits. Type A uses amplitude-shift keying (ASK) with Modified Miller coding from reader to tag, and on-off keying with Manchester coding from tag to reader. Type B, on the other hand, uses ASK with NRZ coding reader-to-tag and binary phase-shift keying (BPSK) with NRZ-L coding tag-to-reader, per ISO/IEC 14443's technical specification. Both still run half-duplex at 13.56 MHz and 106 kbit/s, with a read range up to about 10 cm. Type B isn't faster or longer-range — just a different dialect.
How a reader tells the two apart
Type A and Type B cards can both sit in a reader's field at once, so the reader first has to work out which one it's talking to. It does this with different wake-up commands — REQA/WUPA for Type A, REQB/WUPB for Type B — per NXP's PICC selection application note. A dual-interface reader, like the one in your phone, just polls for both in sequence. You never have to know which standard your card uses.
Where you'll see it
Type A dominates the tags and stickers you'd buy for a DIY project. Type B, though, turns up in a specific set of real-world credentials. EMV contactless payment cards — Visa payWave in particular — are commonly built on Type B, as are some transit fare systems like Calypso and CIPURSE. China's second-generation resident ID card program runs on Type B too.
E-passports and national ID cards are a messier picture. ICAO 9303 requires an ISO/IEC 14443 contactless interface but doesn't mandate a specific sub-type. Most EU passports and ID cards lean Type A, while other national programs use Type B instead. The same split shows up in newer digital-ID formats — see our explainer on mobile driver's license reads for how that plays out on phones. Either way, this is about recognizing which standard a credential uses, not about reading passport or ID data that isn't yours.
Tips, gotchas, and a quick how-to with NFCore
On Android, Type B tags surface through the android.nfc.tech.NfcB class — the same connect-and-transceive shape as NfcA, just aimed at Type B's activation sequence. iOS Core NFC detects Type B too, though the two platforms don't expose identical control to apps. Our iOS vs Android NFC comparison covers what each platform can actually do.
Here's the practical takeaway: almost every blank tag or sticker sold for smart-home triggers, plant care, or business cards is Type A (NTAG21x, MIFARE Ultralight). So if NFCore reports a tag as Type B when you scan it, that's a strong signal you're holding a payment card, transit pass, or ID credential — not something to try to clone or rewrite. Open NFCore and tap a card to see its type reported directly, right alongside the UID.
Frequently Asked Questions
What's the actual difference between NFC-A and NFC-B?
Both run at 13.56 MHz and 106 kbit/s, but they encode bits differently. Type A uses ASK with Modified Miller coding from reader to tag and Manchester coding from tag to reader; Type B uses ASK/NRZ from reader to tag and BPSK/NRZ-L from tag to reader. A reader has to speak both dialects to work with both card families.
Can NFCore read NFC-B tags?
NFCore can detect and inspect ISO 14443 Type B tags the same way it handles Type A — reading the UID and basic card info. But Type B shows up almost exclusively in government ID, transit, and payment credentials, which NFCore won't try to read or clone since that data isn't yours to copy.
Is my passport Type A or Type B?
Depends on the issuing country. ICAO 9303 requires an ISO/IEC 14443 contactless interface but doesn't mandate one sub-type — most EU passports use Type A, while some national ID programs, like China's second-generation resident ID card, use Type B.
Why don't consumer NFC tags and stickers use Type B?
Nearly all NTAG and MIFARE chips — the families used in stickers, wristbands, and DIY automation tags — are built on Type A. Type B chips are more common in cards issued by governments and payment networks, not in the blank tags hobbyists buy.
Conclusion
NFC-A and NFC-B are both legitimate flavors of ISO/IEC 14443, split by modulation and bit-coding rather than speed or capability. Most of the tags you'll ever write yourself are Type A. Type B is what you're carrying when you tap a payment card, a transit pass, or certain national ID documents. With NFC-A, NFC-B, NFC-F (FeliCa), and NFC-V (ICODE) now covered, you've got the full map of the contactless standards NFCore works across.