NPI Numbers in Medical Billing: Type 1 vs Type 2, and Rendering vs Billing Provider

An NPI (National Provider Identifier) is the 10-digit number that identifies a health care provider on every claim, referral and electronic transaction in the United States. It was created by HIPAA, is assigned by CMS, costs nothing, and stays with the provider for life regardless of where they work or which payers they bill. On a claim there are usually at least two: the rendering NPI of the person who performed the service and the billing NPI of the entity being paid.

Most NPI errors on claims come from putting those two in the wrong boxes.

Where you see it

Place	What goes there
CMS-1500 box 17b	NPI of the referring or ordering provider, when the service needs one (consults, diagnostics, DME)
CMS-1500 box 24J, shaded and unshaded	Rendering provider’s NPI for that service line (unshaded); the payer-assigned ID, if any, in the shaded part
CMS-1500 box 32a	NPI of the service facility, when the service was performed somewhere other than the billing provider’s address
CMS-1500 box 33a	Billing provider’s NPI, the entity that receives payment
837P electronic claim	Loop 2010AA (billing), 2310B (rendering), 2310A (referring), 2310C (service facility)
Remittance advice	The REND PROV column on the Medicare remittance in our sample carries the rendering NPI per line
Prescriptions, referrals, prior authorizations	The ordering or prescribing provider’s Type 1 NPI

Type 1 and Type 2

	Type 1	Type 2
Who	an individual: physician, physician assistant, nurse practitioner, physicist, therapist	an organization: group practice, hospital, clinic, lab, DME supplier
How many	one per person, for life	one per organization, and optionally one per subpart (a hospital’s radiation oncology department can have its own)
Used as	rendering, referring, ordering, supervising	billing, service facility, pay-to
Where to get it	NPPES online, about 20 minutes, free	NPPES, applied for by an authorized official of the organization

A physician who practices alone and bills under their own name and tax ID uses their Type 1 in both the rendering and the billing boxes. Once a practice bills under a group name and group tax ID, the group needs a Type 2 for the billing box and each physician’s Type 1 goes in the rendering box.

Rendering, billing, referring, facility: a worked example

Dr. Patel is a radiation oncologist employed by Sample Radiation Oncology, PC. She treats a patient who was referred by Dr. Kim, a urologist, at the practice’s own freestanding center.

Box	NPI	Why
17b referring	Dr. Kim’s Type 1	he ordered the consult
24J rendering	Dr. Patel’s Type 1	she performed the service
32a service facility	left blank	the service happened at the billing provider’s own address
33a billing	Sample Radiation Oncology’s Type 2	the group is paid under its tax ID

Now the same patient is treated at the hospital where the group holds a contract. Box 24J and 33a stay the same; box 32a now carries the hospital’s Type 2 NPI as the service facility, and the place of service becomes POS 22.

If a locum tenens physician covers Dr. Patel for a week, the claim keeps Dr. Patel’s NPI in 24J with modifier Q6 on each line, which is what the Q6 on our sample remittance means: the regular physician’s NPI, the substitute’s services.

NPI is not the same as

• PTAN (Provider Transaction Access Number): Medicare’s own enrollment number, one per provider per contractor and location. The NPI identifies you; the PTAN proves you are enrolled with that Medicare contractor. Both are needed to enroll, but only the NPI goes on the claim.
• Tax ID (EIN or SSN): who gets the 1099. Box 25 on the CMS-1500. One tax ID can have many NPIs billing under it.
• Taxonomy code: the 10-character specialty code attached to the NPI in NPPES (radiation oncology is 2085R0001X). Some payers require it in box 24J shaded or box 33b.
• CAQH ID: the credentialing database number commercial payers use. It is a separate system with a separate number.

What to do

• Check NPPES before the first claim for any new provider. The NPI Registry is public. Confirm the number, the type, and that the taxonomy and practice address are current; a wrong address in NPPES is a frequent cause of Medicare enrollment rejections.
• Keep NPPES current. Changes to name, address or taxonomy must be made within 30 days. An outdated record often goes unnoticed until a claim denies for it.
• Build the rendering-to-billing map once. In Iridium Suite each provider record holds the Type 1, each practice the Type 2, and the claim fills 24J and 33a from the schedule, which removes the hand-entry that causes mismatches.
• Denials to recognize: CARC 16 with remark N290 (missing or invalid rendering provider NPI), N257 (billing provider NPI), N285 (referring provider). Each is a correction and resubmission, not an appeal.

Related terms

• Rendering provider vs billing provider
• PTAN and Medicare enrollment
• Taxonomy codes
• CMS-1500 box by box
• Modifier Q6 and locum tenens billing

Further reading: CMS: National Provider Identifier Standard; NPPES application; NPI Registry lookup.