NFC works for payment but not for tags

Two modes, one antenna

When you pay, the phone emulates a card. The terminal produces the field, and the phone answers inside it.

When you read a tag, the phone is the reader. It produces the field, powers the tag, and receives an answer.

These are opposite roles, handled by different parts of the software, and reached through different settings and permissions. The antenna is the only part they share.

What payment does prove

That the hardware exists and works. The coil, the controller and the antenna path are all functional, because payment used them.

That the antenna is not blocked at the moment of payment, since a metal plate would prevent both.

That NFC is switched on, on Android. Contactless payment uses the same NFC radio a tag reader needs, so a working payment means NFC is enabled rather than off.

That is genuinely useful information. It eliminates a whole class of hardware suspicion and narrows the investigation to the reading path.

What it does not prove

That a given tag will be read and acted on. Payment and reader mode are different software paths, so a working payment does not exercise the one that reads tags, even though the radio it needs is on.

That the phone will act on a tag's content. Reading and acting are separate steps, and a tag holding nothing actionable produces a reaction and nothing else.

That the tag is readable. A chip that is not an NFC Forum tag type will not read on any phone, however healthy that phone is.

On an iPhone it proves less still, because payment has its own dedicated path with different rules from tag reading.

What to check instead

Not the NFC setting on Android. A working payment already shows it is on, so the fault is in the reading path rather than the radio.

A tag you know works, on a phone with the case removed, swept slowly across the back. That establishes reader mode directly.

Which model of iPhone you have, since background reading is available from the iPhone XS and XR onwards and earlier supported models need an application launched manually.

And whether the tag holds content the phone can act on, which is a separate question again and the most common answer when the tag is detected but nothing happens.