Learn what goes in every field, avoid the most common denial triggers, and understand when you need professional billing support.
Check one box only. If the patient has Medicare Advantage (Part C), still check "Medicare." For dual-eligible patients (Medicare + Medicaid), check Medicare if billing primary.
For Medicare: Use the MBI (11-character alphanumeric, e.g., 1EG4-TE5-MK72). Do not use old HICN numbers — Medicare stopped accepting them.
For commercial: Use the member ID exactly as shown on the insurance card, including any prefixes/suffixes.
Enter exactly as it appears on the insurance card. Do not use nicknames. Use legal name only.
Use 8-digit format. Medicare uses DOB to verify eligibility — incorrect DOB = automatic rejection.
Box 4: Name of policyholder (same format as Box 2). Box 6: Self, Spouse, Child, or Other.
When patient IS the insured, enter "SAME" in Box 4 and check "Self" in Box 6.
For Medicare: Leave blank (Medicare doesn't use group numbers). For commercial: Enter exactly as shown on card.
Box 11a: Insured's DOB and sex (when different from patient). Box 11c: Insurance plan name.
Required when services were referred (labs, imaging, specialist visits). Enter referring provider's full name and NPI in Box 17b. Leave blank for primary care self-referral.
This is the individual provider NPI (Type 1), not the group NPI. Required on every service line. Even when billing under a group, the rendering individual's NPI goes here.
Box 32: Address where service was rendered (if different from billing provider).
Box 32a: NPI of the service facility.
Box 33: Billing provider's name and address.
Box 33a: Group/billing NPI (Type 2).
List diagnoses in order of importance to the visit. Slot A is the principal diagnosis (reason for visit). Slots B–L are additional conditions. The ICD Indicator field must show "0" for ICD-10.
24A: Date of Service (MM DD YY — from/to)
24B: Place of Service code (11=Office, 21=Inpatient, 22=Outpatient, 23=ER)
24D: CPT/HCPCS code + modifier (up to 4 modifiers)
24E: Diagnosis pointer — letter(s) from Box 21 that apply (e.g., A, AB, ABC)
24F: Charge amount
24G: Units (days or units)
24J: Rendering NPI
Physician's office, private practice
Inpatient admission
Hospital outpatient department
Hospital emergency department
Ambulatory surgical center
Skilled nursing facility
Long-term care facility
02=Telehealth facility, 10=Telehealth home
Free-standing lab
ESRD treatment facility
Non-hospital outpatient clinic
Home visits, home health
Required fields left blank or containing invalid data.
✅ Fix: Verify all required boxes before submission. NPI, MBI, and DOB are most common.
Box 24E doesn't link to a valid diagnosis code in Box 21.
✅ Fix: Every CPT line must have at least one letter (A-L) in Box 24E matching Box 21.
The ICD-10 code doesn't support medical necessity for the billed service.
✅ Fix: Ensure diagnosis code clinically supports the procedure. Use GMB's AI Coding tool.
Claim submitted after payer's deadline (Medicare = 1 year from DOS).
✅ Fix: Track DOS and submit well within filing window. Set 90-day internal deadline.
NCCI edits bundled the billed code with another service.
✅ Fix: Check CMS NCCI table before billing. Modifier -59 only if truly distinct service.
Box 17/17b blank for services that required a referral.
✅ Fix: Always include referring NPI for specialist services billed to Medicare.
Our team manages multi-payer, secondary claims, and appeals so you focus on patient care.
The 3-digit TOB code defines facility type, bill classification, and frequency. It controls how Medicare processes your claim — wrong TOB = wrong adjudication rules.
First claim for hospital inpatient admission
Continuing inpatient stay claim
Discharge/final bill for inpatient
Outpatient hospital services
Hospital outpatient lab and ancillary
Skilled nursing facility, Part A covered stay
SNF non-covered or Part B services
Medicare home health 60-day episode
Continuing home health episode
Final/discharge home health claim
Routine, continuous, or respite hospice
General inpatient hospice care
FL 8a: Patient Control Number — your internal account number for the patient. Used on remittance advice to match payments.
FL 8b: Patient name (Last, First, MI).
Admission Type: 1=Emergency, 2=Urgent, 3=Elective, 4=Newborn, 5=Trauma
Admission Source: 1=Non-Health Care, 2=Clinic Referral, 4=Transfer from Hospital, 7=Emergency Room
Leave blank for original claims. Code 7 = replacing a previously submitted claim. Code 8 = voiding a claim entirely. Reference the original claim number in the adjacent field.
Enter two-letter state code where accident occurred. Required when services are related to an accident. Works in conjunction with Condition Codes (FL 18-28) to identify accident-related claims.
Required when the responsible party is different from the patient. Common for pediatric patients (parent/guardian) and patients with representative payees.
FL 42: Revenue code (4-digit)
FL 43: Revenue description
FL 44: HCPCS/CPT code (when applicable)
FL 45: Service date
FL 46: Service units
FL 47: Total charges
FL 48: Non-covered charges
FL 67: Principal diagnosis — the condition established after study to be chiefly responsible for the admission.
FL 67A–Q: Additional diagnoses (up to 17 total).
POA Indicator: Y=Yes (present on admission), N=No, U=Unknown, W=Undetermined, 1=Unreported (exempt)
Required for inpatient hospital claims. ICD-10-PCS (not CPT) is used for inpatient procedures. Up to 6 procedure codes + dates. Principal procedure = the one most related to the principal diagnosis.
FL 76: Attending physician (qualifier = DN)
FL 77: Operating physician (qualifier = ZZ)
FL 78-79: Other providers (referring, consulting)
| Rev Code | Category | Description | HCPCS Required? |
|---|---|---|---|
| 0100 | Room & Board | All-inclusive inpatient room and board | No |
| 0120 | Room & Board | Semi-private room — medical/surgical | No |
| 0200 | ICU | Intensive care unit | No |
| 0250 | Pharmacy | General pharmacy | Yes (NDC or HCPCS) |
| 0260 | IV Therapy | IV solutions and infusion | Yes (HCPCS) |
| 0270 | Med/Surg Supplies | Medical and surgical supplies | Yes (HCPCS) |
| 0300 | Laboratory | Clinical laboratory — general | Yes (HCPCS/CPT) |
| 0301 | Laboratory | Chemistry lab | Yes (HCPCS/CPT) |
| 0302 | Laboratory | Immunology lab | Yes (HCPCS/CPT) |
| 0310 | Laboratory Path | Pathology lab (hospital) | Yes (CPT) |
| 0320 | Radiology | Diagnostic radiology — general | Yes (CPT) |
| 0324 | Radiology | Diagnostic radiology — ultrasound | Yes (CPT) |
| 0330 | Radiology Tx | Radiation therapy | Yes (CPT) |
| 0351 | CT Scan | CT scan — head/brain | Yes (CPT) |
| 0352 | CT Scan | CT scan — body | Yes (CPT) |
| 0360 | OR Services | Operating room services | Yes (CPT) |
| 0370 | Anesthesia | Anesthesia services | Yes (CPT) |
| 0420 | Physical Therapy | Physical therapy — general | Yes (CPT + GP) |
| 0430 | Occ Therapy | Occupational therapy — general | Yes (CPT + GO) |
| 0440 | Speech Therapy | Speech-language pathology | Yes (CPT + GN) |
| 0450 | Emergency Room | Emergency room services | Yes (CPT) |
| 0490 | Ambulatory Surgery | ASC or outpatient surgery | Yes (CPT) |
| 0550 | Ambulance | Ambulance services | Yes (HCPCS) |
| 0560 | Home Health | Home health services — medical social services | No |
| 0651 | Hospice | Hospice — routine home care | No |
| 0652 | Hospice | Hospice — continuous home care | No |
| 0655 | Hospice | Hospice — inpatient respite care | No |
| 0656 | Hospice | Hospice — general inpatient (GIP) | No |
| 0001 | Total Charges | Sum of all revenue line charges — always last line | No |
Missing required FLs — attending NPI, TOB, or revenue code.
✅ Fix: Audit FL 4, 6, 7, 42, 67, 76 on every claim before submission.
Provider not authorized for the billed level of care or facility type.
✅ Fix: Verify facility certification/provider enrollment before rendering service.
Service not covered under patient's plan or benefit period.
✅ Fix: Verify benefits and issue ABN when applicable. Use correct condition codes.
Revenue code + HCPCS combination not separately payable.
✅ Fix: Review OPPS bundling rules for outpatient hospital claims.
Statement dates cross benefit period or spell-of-illness boundaries.
✅ Fix: Split claims at benefit period boundaries. Verify FL 6 (statement dates).
Inpatient claim missing Present on Admission indicator on FL 67.
✅ Fix: Every diagnosis on inpatient claim must have a POA indicator (Y/N/U/W/1).
These claim types have additional OASIS, PDPM, and episode-based rules. GMB handles all of it.