X12 837 Part 2: The Claim Information Loop (2300)

Loop 2300 is where the claim stops being an envelope and becomes a medical bill. It holds the claim’s ID and total, where the care happened, the key dates, the prior authorisation number, every diagnosis, repricing results, the providers involved, and whatever other insurance has already paid. If you only learn one loop of the 837, learn this one.

This is part 2 of the 837 series. Part 1 covered the envelopes and hierarchy; Part 3 covers the service lines.

CLM: the claim itself

CLM*PCN000123*270***11:B:1*Y*A*Y*Y~

Element	Meaning
CLM01	Patient control number: the provider’s claim ID, tracked from submission until payment
CLM02	Total claim charge
CLM05-1	837P/D: place of service code (11 office, 21 inpatient hospital, 23 emergency room). 837I: facility type, the first two digits of the bill type (11 hospital inpatient, 13 hospital outpatient)
CLM05-2	B for 837P and 837D; A for 837I
CLM05-3	Claim frequency: 1 original, 7 replacement of a prior claim, 8 void, and, on institutional claims, 5 late charges
CLM06–CLM09	Provider signature, assignment and release-of-information indicators

When CLM05-3 is 7 or 8, the claim being replaced or voided must be identified in REF*F8 (more on that below). Late-charge claims (5) are common for hospitals, which often bill extra charges separately after the original claim.

DTP: claim dates

Each date segment has a qualifier (DTP01), a format (DTP02: D8 for a single date, RD8 for a range), and the value (DTP03).

Qualifier	Date	Used on
431	Onset of current illness	P
439	Accident	P, D
454	Initial treatment, for follow-ups such as physical therapy	P
304	Last seen	P
435	Admission	P, I
096	Discharge	P, I
434	Statement period (RD8 range)	I
452	Orthodontic appliance placement	D
472	Service date	D
050	Repricer received date	All

Statement dates always use RD8 because they’re a from–to range: DTP*434*RD8*20250612-20250618~.

CL1: institutional admission details (837I only)

CL1*1*7*01~

• CL101: admission type: 1 emergency, 2 urgent, 3 elective, 4 newborn, 5 trauma;
• CL102: point of origin (admission source), such as a physician referral or a transfer from another facility; newborns use their own set of codes;
• CL103: patient discharge status, such as 01 (discharged home).

Dental extras: DN1 and DN2 (837D only)

• DN1 gives orthodontic treatment months: the total and remaining.
• DN2 gives tooth status: the tooth number (DN201), status code such as missing or to be extracted (DN202), and the tooth numbering system (DN206 = JP, the Universal National Tooth Designation System).

PWK: attachments

PWK says supporting documents exist: a physician’s order, discharge summary, lab results, X-rays, periodontal charts or dental models. PWK01 is the report type, PWK02 how it’s sent (AA means available at the provider, EL electronically, FX by fax), and PWK06 the attachment control number that links the claim to the documents, which are often sent as a 275.

AMT: what the patient already paid

• AMT*F5: the amount the patient has already paid (837P and 837D, typically outpatient);
• AMT*F3: the patient’s estimated responsibility (837I).

REF: the references that matter

Qualifier	Meaning
G1	Prior authorisation number, from the payer’s 278 response
F8	Payer claim control number: the original claim being replaced or voided
D9	Claim identifier assigned by a transmission intermediary, such as a clearinghouse
9A	Repriced claim reference number, returned by a repricer
9C	Adjusted repriced claim reference number

The repricing references are easiest to understand as a story. A payer sends a claim to its repricer with REF*D9*1234. The repricer returns it with REF*9A*6789. Later the provider disputes the price, so the payer sends it again: a new REF*D9*2214, plus REF*F8*1234 to point at the original. The repricer returns a new REF*9A*1111 and puts its previous number in REF*9C*6789. Every hop stays traceable.

K3 and NTE

• K3 carries fixed-format data that the guide has no segment for, by agreement between trading partners. Use it sparingly.
• NTE carries free-text notes. NTE01 says what the note is about (for example ADD for additional information) and NTE02 holds the text.

HI: diagnoses and procedures

This is the clinical heart of the claim. Each HI element is a composite of a qualifier and a code:

Qualifier	Meaning	Used on
ABK	Principal diagnosis (ICD-10-CM)	P, I, D
ABF	Other diagnosis	P, I, D
ABJ	Admitting diagnosis	I
APR	Patient’s reason for visit	I (outpatient)
DR	Diagnosis-related group (DRG)	I
BBR	Principal procedure (ICD-10-PCS)	I
BBQ	Other procedure	I

(You’ll see BK and BF in old examples. Those are ICD-9 qualifiers and aren’t valid for current dates of service.)

Here’s an inpatient example: a patient admitted with severe cough is diagnosed with pneumonia, has diabetes and hypertension, and is put on a ventilator.

HI*ABK:J189~
HI*ABJ:R059~
HI*ABF:E119*ABF:I10~
HI*DR:208~
HI*BBR:5A1945Z:D8:20250615~
HI*BBQ:3E03329:D8:20250615~

The admitting diagnosis is cough (R05.9), the principal is pneumonia (J18.9), and diabetes (E11.9) and hypertension (I10) are other diagnoses. The principal procedure is ventilation for 24 to 96 hours (5A1945Z), and an anti-infective infusion (3E03329) is another procedure. With ventilator support, this stay would group to a DRG such as 208 (respiratory diagnosis with ventilator support up to 96 hours); the DRG is either assigned by the provider or derived by the payer. Note that codes in X12 have no decimal point: J18.9 becomes J189.

Professional and dental claims only use ABK and ABF.

HCP: repricing results

Repricers return their result in HCP: HCP01 the pricing method, HCP02 the allowed amount, HCP03 the savings, and HCP13 a reason if the claim couldn’t be repriced. Claim Repricing covers it in detail.

2310 loops: the providers

NM101	Role	Typical claim
DN / P3	Referring provider / primary care provider	P
71	Attending physician	I
72	Operating physician	I
82	Rendering provider: who actually performed the service, if different from the billing provider	P, D, I
77	Service facility location	All

People use NM102 = 1; facilities use 2. NM108 = XX puts the NPI in NM109. Secondary IDs go in REF segments, such as 0B (state licence number) or G2 (the payer’s own provider number).

2320 and 2330: other insurance

When the patient has more than one plan, loop 2320 describes the other coverage, and 2330 names the other subscriber (NM1*IL) and other payer (NM1*PR).

SBR*P*01*GRP555******CI~
CAS*PR*1*100~
AMT*D*170~
OI***Y***Y~
NM1*IL*1*DOE*JANE****MI*X99887766~
NM1*PR*2*OTHER HEALTH PLAN*****PI*OTHER01~

That says the other plan is the primary payer (SBR01 = P), so this claim is going to the secondary; the patient is the subscriber’s spouse (SBR02 = 01), the other payer has already paid $170 (AMT*D), and $100 was patient responsibility for the deductible (CAS*PR*1). The receiving payer uses this to coordinate benefits without overpaying.

CAS adjustments use a group code (CO contractual obligation, PR patient responsibility, OA other adjustment, PI payer-initiated) plus a claim adjustment reason code (CARC) and an amount.

Common pitfalls

• Using CLM05-1 as place of service on an 837I. It’s the facility type from the bill type.
• A replacement claim without REF*F8. The payer can’t find what you’re replacing.
• Decimal points in codes. J18.9 is sent as J189.
• ICD-9 qualifiers (BK, BF) on modern claims.
• Missing REF*G1 when the service needed prior auth.

Conclusion

Loop 2300 holds the claim: its ID and total (CLM), setting and frequency (CLM05), dates (DTP), institutional and dental extras (CL1, DN1, DN2), attachments (PWK), references (REF), diagnoses and procedures (HI), repricing (HCP), providers (2310) and other insurance (2320/2330).

Continue with Part 3: Service Lines (Loop 2400).

Further watching

From the HealthTech Decoded channel:

• Chapter 2: How to master X12 837 (loop 2300)
• Chapter 2: X12 837 (short)

References

• CMS: Place of Service code set
• X12: Claim Adjustment Reason Codes
• Stedi: X12 837P reference

Where this fits

Level 3 · Health data exchange › Healthcare EDI (ANSI X12)

• Previous: X12 837 Part 1: Submitter, Receiver, Provider, Subscriber and Patient Loops
• Next: X12 837 Part 3: Service Lines (Loop 2400)