Can NFC interfere with wireless charging?
Yes, in both directions. Wireless charging and NFC both work by coupling coils, at different frequencies but in the same few centimetres of space. A tag placed over a charging coil is typically unreadable, and a tag left on a pad can disturb charging or heat up.
The same space, different frequencies
Wireless charging pads operate at a much lower frequency than the 13.56 MHz NFC uses, and they move watts rather than microwatts. The Qi specification published by the Wireless Power Consortium puts the operating frequency between 87 and 205 kHz.
Different frequencies would suggest they ignore each other, and they do not, because the problem is not spectral. It is that a charging coil is a large conductor with many turns sitting exactly where an NFC antenna needs clear space, and a coil near another coil detunes it regardless of what frequency either is operating at.
A tag over a charging coil
Sticking a tag to the back of a phone that supports wireless charging is one of the most reliable ways to make a tag unreadable, and one of the most commonly attempted.
The charging coil occupies the middle of the phone's back, which is also close to where the NFC antenna lives. A tag placed there is coupling with a large coil at point blank range instead of with the reader, and the read fails.
The same applies to a tag on a charging pad, or on any surface with a coil hidden under it, including some car mounts and desk stands.
A tag left on a pad
The reverse case is less common and worth knowing because it can do damage.
A charging pad delivers real power, and a metal object or a coil left on it absorbs some of that power as heat. Chargers include foreign object detection intended to notice this and stop, and detection is not infallible with thin objects.
A card left on an active pad can warm up. Whether that reaches a temperature capable of damaging the chip depends on the charger, the card and how long it sits there, which is why leaving cards on pads is worth avoiding even though most such incidents are harmless.
How to avoid the collision
If a phone must carry a tag, put it on the case rather than the phone, offset well away from the centre, and test both tag reading and wireless charging afterwards. Expect to move it more than once.
If a tag must live on a surface that also charges, do not. Place it beside the charging area rather than on it, and accept that a few centimetres of separation is the whole solution.
And in a deployment where users will place phones on stands or mounts, expect this to happen without anyone reporting it as a cause. The complaint will be that the tag stopped working, and the mount will not be mentioned.
Frequently asked questions
Can wireless charging damage an NFC tag?
It is possible through heating rather than through the field itself, and it is uncommon. Foreign object detection usually prevents it, and the practical advice is simply not to leave cards or tags on an active pad.
Why does my phone stop reading tags on a car mount?
Either the mount contains a charging coil, or it contains a metal plate for magnetic attachment. Both sit over the antenna and both prevent reads, and they are frequently combined in the same product.
Can I use a tag and wireless charging on the same phone?
Yes, if the tag is offset from the charging area, usually towards an edge of the case. Finding a position that satisfies both takes trial and error and is worth doing before gluing anything.
Does NFC interfere with charging, or only the other way round?
Both directions occur. A tag on a pad can disturb the charger's detection, and a charging coil detunes a nearby tag. In practice the second is far more often the complaint.