The NPI and tax ID fields on claim forms identify who did the work and who gets paid. On the CMS-1500, NPIs sit in boxes 17b, 24J, 32a and 33a, and the tax ID in box 25. On the UB-04, the billing NPI is FL 56, the tax number FL 5, and clinician NPIs FL 76 to 79.
Where NPI and tax ID numbers sit on the CMS 1500
The CMS 1500 is the paper claim for professional services, and it carries up to four different National Provider Identifiers (NPIs) plus one federal tax ID. An NPI is the 10-digit number that identifies a health care provider. Each NPI box answers a different question about the claim.
The NUCC 1500 Claim Form Reference Instruction Manual, the industry guide for the 02/12 form, assigns them this way:
- Box 17b holds the NPI of the referring, ordering or supervising provider named in box 17. A qualifier beside box 17 (DN, DK or DQ) says which role that person played.
- Box 24J holds the rendering provider's NPI in the lower, unshaded half of each service line. The shaded upper half is for a non-NPI number with its qualifier in 24I. NUCC says to report 24I and 24J only when they differ from 33a and 33b.
- Box 25 holds the federal tax ID of the billing provider in box 33, either an employer identification number (EIN) or a Social Security number (SSN). A checkbox says which one it is. NUCC calls it the number "intended to be used for 1099 reporting purposes" and says to enter it without hyphens.
- Box 32a holds the NPI of the service facility, the place where care happened. NUCC says to report it only when it differs from the billing NPI.
- Box 33a holds the billing provider's NPI, the entity asking to be paid.
Medicare adds its own rules on top. The Medicare Claims Processing Manual, chapter 26 calls 33a "the NPI of the billing provider or group" and marks it required. It says 17a and the shaded part of 24J are not reported. It also says that a claim sent without tax information in box 25 may see its reimbursement delayed.
The full list of billing provider boxes, including addresses and the signature in box 31, is covered in the guide to CMS 1500 billing provider boxes 25 to 33.
Where NPI and tax ID numbers sit on the UB-04
The UB-04 is the institutional claim used by hospitals and other facilities, and it places identifiers in separate form locators (FLs) rather than in one provider block. A form locator is a numbered field on the UB-04. Three groups matter: the tax number, the billing NPI and the clinician identifiers.
The Medicare Claims Processing Manual, chapter 25 describes them:
- FL 5, Federal Tax Number, is required, and its format is given as NN-NNNNNNN. The hyphen is part of the printed format here, unlike box 25 on the CMS-1500.
- FL 56, Billing Provider National Provider ID, has been required since May 23, 2008.
- FL 57, Other Provider ID, is "not used" for Medicare, and data entered there is ignored.
- FL 76 holds the attending provider's name and identifiers, including the NPI. The attending provider has overall responsibility for the patient's care on the claim.
- FL 77 holds the operating provider, required when a surgical procedure code is on the claim.
- FL 78 and 79 hold other providers, each with a qualifier: DN for a referring provider, ZZ for another operating physician and 82 for a rendering provider.
The UB-04 has no single box for a referring NPI the way the CMS-1500 has 17b. A referring provider goes in FL 78 or 79 with the DN qualifier, and only on an outpatient claim when that person differs from the attending physician.
Box map for both forms
| # | Form | Box or FL | Whose number it is |
|---|---|---|---|
| 1 | CMS-1500 | 17b | Referring, ordering or supervising provider's NPI |
| 2 | CMS-1500 | 24J (unshaded) | Rendering provider's NPI, per service line |
| 3 | CMS-1500 | 25 | Billing provider's EIN or SSN |
| 4 | CMS-1500 | 32a | Service facility's NPI, when different from billing |
| 5 | CMS-1500 | 33a | Billing provider's or group's NPI |
| 6 | UB-04 | FL 5 | Billing facility's federal tax number |
| 7 | UB-04 | FL 56 | Billing provider's NPI |
| 8 | UB-04 | FL 76 | Attending provider's NPI |
| 9 | UB-04 | FL 77 | Operating provider's NPI |
| 10 | UB-04 | FL 78 and 79 | Other providers' NPIs, with a role qualifier |
Is the billing NPI the same as the rendering NPI?
The billing NPI and the rendering NPI are often different numbers. The billing NPI names the entity that gets paid, usually a group or facility. The rendering NPI names the individual who performed the service. They match only when a solo clinician bills under their own NPI.
The CMS NPI fact sheet explains why. A Type 1 NPI is for individual providers such as physicians, nurse practitioners and sole proprietors, and an individual is eligible for only one. A Type 2 NPI is for organizations such as hospitals, nursing homes and physician groups, and an organization can have several. An incorporated clinician can hold both a Type 1 for themselves and a Type 2 for the corporation.
Read the roles on a claim this way:
- Billing NPI (33a, FL 56): who is asking to be paid. Usually a Type 2.
- Rendering NPI (24J, or FL 78 and 79 with qualifier 82): who did the work. Usually a Type 1, though NUCC lets a laboratory or other facility be the rendering provider.
- Referring or ordering NPI (17b, or FL 78 and 79 with qualifier DN): who sent the patient or ordered the service. An individual, so a Type 1.
- Service facility NPI (32a): where the service happened, when that place is a separate organization from the billing provider.
NUCC adds a rule that trips people up. If a service location is a subpart of the billing provider with its own NPI, the subpart is reported as the billing provider, and 32a is left empty. An NPI in 32a must belong to an organization outside the billing provider.
How can you check an NPI or tax ID before a claim goes out?
An NPI can be checked two ways before a claim goes out: by its check digit and by a registry lookup. A tax ID can be checked by its shape. These checks catch typos and swapped fields. They do not confirm that a provider is licensed or enrolled with a plan.
The NPI check digit
The 10th digit of an NPI is a check digit. The CMS paper on NPI check digit requirements says it uses the Luhn formula, with a constant of 24 added to stand in for the 80840 prefix used on health ID cards. It also says NPIs are issued with a first digit of 1 or 2.
Here is the calculation for the example NPI 1234567893 that CMS uses in that paper:
| Step | Work | Result |
|---|---|---|
| Take the first nine digits | 1 2 3 4 5 6 7 8 9 | |
| Double every other digit, starting from the rightmost | 9, 7, 5, 3, 1 become 18, 14, 10, 6, 2 | |
| Add the digits of the doubled values | 1+8 + 1+4 + 1+0 + 6 + 2 | 23 |
| Add the digits that were not doubled | 8 + 6 + 4 + 2 | 20 |
| Add the constant 24 | 23 + 20 + 24 | 67 |
| Subtract from the next number ending in zero | 70 minus 67 | 3 |
The check digit is 3, so 1234567893 passes. If someone keys 1234567839 instead, the last digit no longer matches the calculation, and the number fails before any payer sees it.
Registry lookup and tax ID shape
A passing check digit only proves the number is well formed. The fact sheet says the National Plan and Provider Enumeration System (NPPES) assigns NPIs and "is the database that stores and manages all NPIs". The public NPPES NPI Registry lets anyone look up an NPI. The same fact sheet warns that having an NPI does not mean a provider is licensed, credentialed or enrolled in a plan.
For tax IDs, both kinds have nine digits but group them differently. The IRS page on taxpayer identification numbers says an SSN is issued by the Social Security Administration and shows the SSN layout as NNN-NN-NNNN. Chapter 25 gives the UB-04 tax number layout as NN-NNNNNNN, two digits then seven, while the SSN groups its nine digits as three, two and four. The IRS page on employer ID numbers calls an EIN "a federal tax ID number for businesses, tax-exempt organizations and other entities". A box 25 entry with the EIN checkbox marked should be a business or other entity's number, not an individual's SSN.
The wider set of format and cross-field checks for extracted claims has its own section on format checks for extracted claim codes and identifiers.
Swapped NPI and tax ID values on claim forms
A swapped NPI or tax ID on a claim form puts a valid number in the wrong box. A group NPI lands in a rendering box, an individual NPI lands in 33a, or the tax ID does not belong to the billing provider. Every number can pass its own format check while the claim still describes the wrong payee.
Each mix-up below breaks a NUCC or CMS instruction for that box:
- Group NPI in 24J. Box 24J asks for the person who rendered the service. A Type 2 group number there tells the payer that an organization performed the visit. If the rendering and billing providers really are the same, NUCC says to leave 24I and 24J empty and let 33a stand.
- Individual NPI in 33a with a group tax ID in 25. Box 25 must be the tax ID of the provider in box 33. An individual's NPI in 33a paired with a group EIN in 25 describes two different payees on one claim.
- SSN with the EIN box checked. The checkbox in box 25 is a separate field from the number. A nine-digit SSN marked as an EIN is a common keying slip.
- Service facility NPI that repeats the billing NPI. NUCC says 32a is reported only when it differs from the billing NPI. A copy of 33a in 32a adds nothing and can confuse an edit.
- Rendering NPI on a UB-04 in the wrong locator. On the UB-04 the attending provider goes in FL 76. A rendering provider goes in FL 78 or 79 only with qualifier 82, and chapter 25 limits that to combined facility and professional claims.
Chapter 26 sets the stakes for Medicare. Claims with incomplete or invalid information "may be returned to the submitter as unprocessable".
These numbers are also where paper claims and scanned images fail. The guides on reading CMS-1500 forms with OCR and reading UB-04 forms with OCR cover how digits in boxes 24J, 33a and FL 56 get misread. A plan's own identifiers, such as the member ID and group number, are a separate set of fields covered in the guide to the member ID and group number on insurance cards.
When Schema Care reads a claim, each NPI and tax ID field comes back with a confidence score and a link to its box on the page. Any value under the threshold your team sets waits in a review queue, and the human review step shows the reviewer that box on the original image.