Medical Billing Glossary
Every term your medical bill uses, explained the way a knowledgeable friend would.
Most Important Terms
EOB — Explanation of Benefits
A document from your insurance company after a medical visit. NOT a bill. Many people pay it by mistake. Wait for a separate bill from your doctor.
How to read it:
- Amount Billed — what the doctor originally charged
- Allowed Amount — what your insurance agreed the service is worth
- Plan Paid — what your insurance actually paid
- Your Responsibility — what you actually owe (ONLY this column)
Deductible
The amount you pay each year before insurance starts paying. Example: $1,500 deductible means you pay the first $1,500 yourself. Resets January 1st.
Copay
A fixed amount you pay per visit. Example: $30 every primary care visit. Applies even before you've met your deductible.
Coinsurance
The percentage you pay after your deductible is met. Example: 20% coinsurance on a $500 procedure = you pay $100, insurance pays $400.
Out-of-Pocket Maximum
The most you'll pay in one year. After this, insurance pays 100%. Track this number — if you're close to it, schedule procedures before year-end.
In-Network vs. Out-of-Network
In-network: provider has agreed with your insurer. You pay less.
Out-of-network: no agreement. You pay much more, sometimes everything.
Even in-network hospitals can have out-of-network doctors (anesthesiologists, etc.). Ask beforehand.
CPT Codes — What You Were Charged For
CPT = Current Procedural Terminology. Five-digit numbers for every medical service.
Office Visits
| Code | Plain-English Meaning |
|---|---|
| 99202 | New patient, simple — ~15–29 min |
| 99203 | New patient, moderate — ~30–44 min |
| 99204 | New patient, complex — ~45–59 min |
| 99211 | Established patient, brief (nurse visit) |
| 99212 | Established patient, simple — ~10–19 min |
| 99213 | Established patient, moderate — ~20–29 min |
| 99214 | Established patient, complex — ~30–39 min |
| 99215 | Established patient, very complex — 40+ min |
Watch for:If you've seen this doctor before, you should be “established patient” (99211–99215), not “new patient” (99202–99204). New patient codes cost more.
Preventive Care (usually 100% covered)
| Code | Meaning |
|---|---|
| 99391–99397 | Annual wellness exam, established patient |
| G0438 | Medicare Annual Wellness Visit (first time) |
| G0439 | Medicare Annual Wellness Visit (subsequent) |
Common Tests
| Code | Meaning |
|---|---|
| 93000 | EKG — heart rhythm |
| 85025 | Complete blood count (CBC) |
| 80053 | Comprehensive metabolic panel |
| 83036 | HbA1c (diabetes test) |
| 71046 | Chest X-ray, 2 views |
| 70553 | MRI of brain with contrast |
| 27447 | Total knee replacement |
| 66984 | Cataract surgery with lens implant |
ICD-10 Codes — Why You Were Treated
| Code | Meaning |
|---|---|
| Z00.00 | Annual wellness exam |
| I10 | High blood pressure |
| E11.9 | Type 2 diabetes, no complications |
| M79.3 | Sciatica |
| J06.9 | Upper respiratory infection |
| M17.11 | Right knee arthritis |
| F41.1 | Generalized anxiety disorder |
Revenue Codes (Hospital Bills Only)
| Code | Meaning |
|---|---|
| 0110–0119 | Room & board |
| 0250 | Pharmacy (medications given in hospital) |
| 0300–0309 | Laboratory |
| 0320 | Radiology (X-rays) |
| 0324 | CT scan |
| 0360 | Operating room |
Ask for an itemized bill — you have the legal right to see every line item.
Common Billing Errors
Duplicate billing — Same service billed twice. Look for same date + same code + same amount twice.
Upcoding — More expensive code used when simpler one was appropriate. Example: 99214 billed for what was a routine 99213 visit.
Wrong patient — Charges from another patient on your bill. Check all names, dates, services.
Unbundling — Billing separately for services that should be grouped as one charge.
Balance billing (surprise billing) — Charged the gap between provider's rate and insurance payment, when provider is in-network. Federal law prohibits this in most cases.
Your Rights
No Surprises Act (2022): No balance billing for emergency care. No out-of-network charges at in-network facilities without written notice.
Right to itemized bill: Legal right at any hospital or provider. If refused, contact your state insurance commissioner.
Right to dispute: Insurance companies must provide an appeals process with specific timeframes.
Medical debt + credit (2026): Debts under $500 not reportable. Paid debt removed immediately. You cannot be denied a loan solely because of medical debt.
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