Updated 2026-07-31
Verifying an NPI has three layers. Format validity: an NPI is 10 digits whose last digit is a Luhn check digit computed with the healthcare prefix 80840, so most typos fail instantly. Registry status: the NPPES registry says whether the number is actually assigned and active, or deactivated with a date. Identity: the record's name, entity type, and taxonomy must match the provider you mean. NPI Registry Lookup runs all three — the check digit as you type, then a live registry query with the record's details.
NPIs are not arbitrary: the tenth digit is a check digit computed with the Luhn algorithm over the first nine, using the healthcare identifier prefix 80840. A transposed or mistyped digit almost always breaks the checksum, so a format check catches most bad numbers before any lookup runs — this site validates it as you type.
A number that passes the checksum is only well-formed. Passing says nothing about whether the NPI was ever assigned to anyone.
The NPPES registry is the authority on whether an NPI is assigned and active. The lookup queries it live and shows the record's status — including deactivation and reactivation dates when the registry carries them — with the query timestamp on the result.
A number not found in the registry at query time is not proof of anything beyond that — recheck the digits, and remember absence from any public file is never a negative finding here.
A valid, active NPI can still be the wrong NPI. Confirm the record's name, entity type — see Type 1 vs Type 2 NPIs — taxonomy, and location against the provider you intend. Common names collide, and practitioners who work at organizations have both personal and organizational NPIs in play.
Registry data is identity, not authorization: an active NPI does not verify licensure, credentialing, or Medicare enrollment. The lookup shows the public Medicare signals separately, each with its own source and vintage.
Yes. The checksum only proves the number is well-formed. Roughly one in ten random 10-digit strings passes it, so the live registry query is what confirms assignment and status.
The registry can deactivate an NPI — NPPES's reason codes cover death, disbandment, and fraud, with everything else grouped under other — and it records the date. That is an NPPES identifier status, separate from any Medicare enrollment status, and the lookup shows the registry's dates when they exist.
Verify any NPI free — check digit, live registry status, and identity details in one lookup with timestamp evidence