NPI vs Tax ID: What's the Difference?
Healthcare providers use multiple identifiers. The two most commonly confused are the NPI (National Provider Identifier) and the Tax ID (TIN/EIN). While both are used in billing, they serve very different purposes.
NPI Number
- Purpose: Identifies the healthcare provider
- Issued by: CMS (NPPES)
- Format: 10-digit number
- Who gets one: Healthcare providers and organizations
- Used for: HIPAA transactions, claims, referrals
- Duration: Permanent (lifetime)
- Cost: Free
- Public: Yes - searchable in NPPES registry
Tax ID (TIN/EIN)
- Purpose: Identifies the taxpayer for IRS
- Issued by: IRS
- Format: 9-digit number (XX-XXXXXXX)
- Who gets one: Any business or individual
- Used for: Tax reporting, payment processing
- Duration: Permanent
- Cost: Free
- Public: No - confidential
When to Use Each
| Scenario | NPI | Tax ID |
|---|---|---|
| Filing electronic claims | Yes | Yes |
| Ordering DME/supplies | Yes | No |
| Referrals/authorizations | Yes | No |
| Receiving payments | No | Yes |
| Tax reporting (1099s) | No | Yes |
| E-prescribing | Yes | No |
| PECOS enrollment | Yes | Yes |
Key Differences
- One provider, multiple Tax IDs: A physician who works at multiple practices may bill under different Tax IDs but always uses the same NPI.
- Tax IDs are confidential: Unlike NPI numbers which are publicly searchable, Tax IDs should never be shared publicly.
- Claims need both: Most electronic claims require both the rendering provider's NPI and the billing entity's Tax ID.
- NPI replaced other IDs: The NPI replaced UPIN, Medicare PIN, and other identifiers. Tax IDs were not affected.
For DME Companies
When processing a DME order, you need:
- Ordering physician's NPI - to verify PECOS enrollment and DME ordering eligibility
- Your organization's NPI - as the rendering/billing provider
- Your organization's Tax ID - for payment routing
You do NOT need the ordering physician's Tax ID - only their NPI.
Need to verify a provider's NPI?
Search NPI Numbers