What is ISO/IEC 14443, and which tags follow it?
ISO/IEC 14443 is the standard for proximity cards at 13.56 MHz. It defines how a reader and a card find each other, agree to talk and exchange frames. Most consumer NFC tags and every contactless bank card build on it, in one of two variants known as Type A and Type B.
A standard in layers
ISO/IEC 14443 is not one thing. It is split into parts that stack: the physical characteristics of a card, the radio interface and how a card is powered, the initialisation and anticollision procedure, and finally the transmission protocol used once a card has been selected.
That last layer is the one developers meet by name. Android calls it ISO-DEP and documents it as ISO 14443-4 in its NFC technology reference.
Type A and Type B
The standard defines two incompatible ways of encoding the signal in each direction. Both work at 13.56 MHz, both are covered by the same standard, and a compliant reader supports both.
Type A is overwhelmingly what you meet in consumer tags. Type B turns up in identity documents and in some national card schemes. Android exposes them separately as NfcA, documented as ISO 14443-3A, and NfcB, documented as ISO 14443-3B.
For a buyer this distinction is almost always irrelevant, because phones handle both. It becomes relevant only when a specific reader or a specific badge system supports one and not the other.
How your phone exposes it
| Android name | Standard | What it gives you |
|---|---|---|
| NfcA | ISO 14443-3A | Low level access to a Type A tag |
| NfcB | ISO 14443-3B | Low level access to a Type B tag |
| IsoDep | ISO 14443-4 | The transmission protocol, used by cards and Type 4 tags |
Seeing several of these listed for a single tag is normal rather than a contradiction. A Type 4 tag legitimately presents NfcA and IsoDep at once, because the layers stack.
When it matters to you
Three situations, and only three.
When a supplier tells you a tag is 14443 compliant and nothing more, that is not enough information: it says nothing about the tag type, the memory or whether NDEF is supported. Push for the tag type.
When an existing access system is involved, the variant matters, because a reader built for Type B will not read your Type A tags no matter how compliant both are.
And when an application reports a tag as ISO-DEP with no NDEF, you are looking at a card rather than a tag: something built to run a protocol, not to hand over stored content.
Frequently asked questions
Is my contactless bank card ISO 14443?
Almost certainly yes, at the radio layer. The payment application running on top of it is specified separately by EMVCo. This is why a phone can detect the card and read a few technical details while being unable to do anything meaningful with it.
Can I link to the ISO standard itself?
The text is sold rather than published openly, and the ISO site blocks automated access, which is why this site cites the standard by number and links to documentation that quotes it rather than to a paywalled page.
What is the difference between 14443 and NFC?
14443 is one of the standards NFC builds on. NFC adds a data format, tag types and the ability for a device to act as either side of the exchange. Every NFC device speaks 14443, but plenty of 14443 systems are not NFC.
Does Type A or Type B read further?
Neither, in any way you would notice. Read distance is set by antenna geometry and by the field the reader produces, not by which encoding the two ends agreed on.