How do you erase an NFC tag?
Write an empty message, or format the tag, and it reads as blank. Neither operation wipes the memory: the old bytes may physically remain outside the declared message length, so a tag that held something sensitive is not made safe by either method.
Two ways, both adequate for normal use
Writing an empty message is the light option. The tag keeps its structure, the declared content length becomes zero, and any reader sees a blank tag.
Formatting is the heavier option. It rebuilds the structure as well as clearing the content, which is useful if the structure was damaged and unnecessary otherwise.
For the ordinary case of reusing a tag, either works and the first is faster.
What erasing does not do
It does not overwrite the memory. Declaring a message empty tells readers to stop looking, it does not scrub the bytes that were there.
Anything reading raw memory blocks rather than going through the content layer may therefore still find remnants of what was written. That is not exotic: raw block access is available on many chip families and exposed by ordinary tools.
Nor does it touch the identifier, the configuration, any password area, or data you deliberately stored outside the content region.
If the content was sensitive
Overwrite rather than erase. Write a message that is at least as long as the one you are replacing, filled with something meaningless, and then write an empty message if you want the tag to read as blank.
That leaves nothing recoverable through the content layer or through raw blocks, because the bytes themselves are gone rather than merely unreferenced.
And consider whether the tag should be reused at all. Tags cost cents, and a tag that carried a credential or a personal detail is cheap to destroy and awkward to be confident about.
When you cannot erase at all
A locked tag. Locking makes the memory read only, permanently, and no operation removes that. Whatever was on the tag when it was locked stays there for the life of the tag.
This is worth stating plainly because it catches people who assumed locking was reversible or that formatting would override it. It is not, and it does not.
A password protected tag can be erased with the password and not without it, which is a protection rather than a permanent state.
Frequently asked questions
Is writing an empty message the same as formatting?
Not quite. Both leave the tag reading as blank, and formatting also rebuilds the structure. If the structure is healthy, an empty write is sufficient and cheaper.
Can someone recover what was on an erased tag?
Through raw memory access, potentially, since erasing does not overwrite the bytes. For anything sensitive, write over the old content before clearing it.
Does erasing reset the tag counter?
No. Counters on chips that have them are separate from the content region and are generally designed to be one way, so they cannot be reset by erasing or formatting.
Can I erase a locked tag?
No. Locking is permanent and applies to the whole memory, so the content stays exactly as it was when the tag was locked.