To bill insurance as a healthcare provider, you complete credentialing and enrollment with each payer, verify the patient’s coverage before treatment, document and code the service accurately, submit a clean claim within the payer’s filing deadline, then reconcile the payment and appeal any denials. Each step has its own rules, and skipping or fumbling one is what turns a routine visit into an unpaid claim.
Get Credentialed and Enrolled First
No insurer will pay you until it has verified who you are. Credentialing is the payer’s review of your education, training, board certifications, malpractice coverage, and work history. Most major health plans accept the Council for Affordable Quality Healthcare (CAQH) ProView application, a single standardized online form used in all 50 states.1CAQH. Solutions Credentialing Map Factsheet Plan on 60 to 180 days from submission to approval.
You also need an active state license for your profession. Requirements vary by state but generally include a national board exam, continuing education, and malpractice coverage, and some states add prescription drug monitoring participation or background checks.
Once you’re credentialed and licensed, you enroll with each payer you plan to bill. Enrollment ties your credentials to the insurer’s billing system and typically asks for your Tax Identification Number, National Provider Identifier, and banking details for electronic payments.2Centers for Medicare & Medicaid Services. Apply for an NPI – NPPES Some payers also require a signed participation agreement setting your reimbursement rates.
For Medicare, add one more step: an Electronic Data Interchange (EDI) enrollment form filed with your local Medicare Administrative Contractor before you can submit electronic claims, whether directly or through a clearinghouse.3Centers for Medicare & Medicaid Services. How to Enroll in Medicare Electronic Data Interchange Organizations with multiple provider numbers can file one form covering all components, but the organization is on the hook for everything submitted under it.
Verify Coverage Before You Treat
Insurance details change at least annually, so check active enrollment, deductible balance, copays, and benefit limits for every visit — not just for new patients. Most payers offer an online eligibility portal or a phone verification line for real-time checks.
Some services need prior authorization, meaning the insurer reviews medical necessity before agreeing to pay. Skip that step and you’ll get a flat denial, leaving either you or the patient with the bill. Payers can also cap the number of visits or units of a service within a benefit period, so confirm those limits before scheduling anything ongoing.
When a patient carries more than one policy, work out coordination of benefits so you know which plan pays first. The primary insurer pays at its full benefit level; the secondary picks up some or all of the remainder. Get the order wrong and both payers usually deny. Most states follow the NAIC model rules for determining the order.4National Association of Insurance Commissioners. Coordination of Benefits Provisions
Code the Service Accurately
Every claim rides on standardized codes. ICD-10 categorizes diagnoses. CPT, maintained by the American Medical Association, describes the services and procedures you performed. HCPCS covers items outside CPT, like durable medical equipment and ambulance services.5Centers for Medicare & Medicaid Services. Code Sets Overview One wrong digit can produce a denial or an underpayment that takes weeks to unwind.
Modifiers are two-character additions to CPT codes that flag special circumstances, like a procedure done on multiple anatomic sites or one that was reduced in scope. Wrong modifier or missing modifier — either bounces the claim. And the documentation in the chart has to match every code and modifier on the claim. Any gap between what you wrote and what you billed reads to the payer as a red flag.
CMS publishes the National Correct Coding Initiative (NCCI), which runs two kinds of automated edits before a Medicare Part B claim pays:
- Procedure-to-Procedure edits flag CPT/HCPCS pairs that generally shouldn’t be billed together on the same date of service unless the procedures happened at separate encounters or anatomic sites.
- Medically Unlikely Edits set a maximum number of units for a single code per provider per patient per day.
Many private insurers apply the same logic in their own systems.6Centers for Medicare & Medicaid Services. Medicare NCCI FAQ Library Running your code combinations against the current NCCI tables before submission prevents a large share of avoidable denials.
Submit the Claim on Time
Most claims go out electronically through a clearinghouse, which sits between your practice management system and the payer. The clearinghouse runs front-end edits for missing fields, invalid codes, and formatting errors, and kicks back anything that fails before it ever reaches the insurer. A well-run billing operation aims for a first-pass acceptance rate above 95 percent.
The form depends on what kind of provider you are. Professional and outpatient physician services go on the CMS-1500, with required fields for the patient’s insurance ID, dates of service, place-of-service codes, diagnosis codes linked to each procedure, HCPCS/CPT codes, charges, and the rendering provider’s NPI.7Centers for Medicare & Medicaid Services. Medicare Claims Processing Manual – Chapter 26 Institutional providers, including hospitals and skilled nursing facilities, use the UB-04 (also called the CMS-1450), which adds fields for type-of-bill codes, revenue codes, and discharge status.8Centers for Medicare & Medicaid Services. Medicare Claims Processing Manual – Chapter 25
Every payer sets a timely filing deadline, and missing it forfeits payment. No appeal fixes a late-filed claim. Medicare gives you 12 months from the date of service.9Medicare.gov. Filing a Claim Commercial payers set their own windows, commonly 90 days to one year. The safe practice is to file within days of the encounter.
Track Payment and Reconcile
Once a claim reaches the payer, it enters adjudication. Automated systems check coding, duplicates, eligibility, and medical necessity. Routine claims typically process in 14 to 30 days; complex cases or ones needing medical records take longer.
Approved claims pay by electronic funds transfer or paper check, along with an Explanation of Benefits or Electronic Remittance Advice. Those documents break down what the plan paid, what went to the patient’s deductible, the patient’s copay or coinsurance, and any contractual write-off. Reconciling every remittance against your accounts receivable is where errors get caught or missed. If a payment doesn’t match your contract, investigate right away rather than letting it age.
Whatever the payer applies to deductible, copay, or coinsurance is the patient’s responsibility. Send patient statements promptly after the remittance posts. Waiting months makes collection harder and confuses patients about what they owe.
Work Denials Quickly
Every denial arrives with a Claim Adjustment Reason Code (CARC) telling you why the claim didn’t pay. Common ones:
- CARC 16 — missing information or data error.
- CARC 18 — duplicate claim.
- CARC 29 — timely filing exceeded.
- CARC 50 — not medically necessary.
- CARC 96 — non-covered service.
- CARC 97 — included in another service (bundled).
- CARC 197 — prior authorization missing.
Administrative errors like CARC 16 or 18 usually just need a corrected resubmission. Policy denials like CARC 50 or 197 require a formal appeal with clinical documentation. Under the ACA, health plans must give you at least 180 days from the denial notice to file an internal appeal.10Centers for Medicare & Medicaid Services. Has Your Health Insurer Denied Payment for a Medical Service – You Have a Right to Appeal A strong appeal includes the relevant records, a letter explaining medical necessity, and any clinical guidelines or payer policies backing you up. An appeal filed one day late is the same as no appeal.
Insurers can also claw money back after they’ve paid. Medicare’s rule sets a six-year lookback: overpayments must be reported and returned if identified within six years of receipt.11Federal Register. Medicare Program – Reporting and Returning of Overpayments Commercial payers set their own recoupment windows in their provider agreements. If your notes from three years ago don’t support the codes you billed, you’ll be writing a refund check.
What You Can and Can’t Bill the Patient
Federal law limits balance billing in certain situations. Under the No Surprises Act, in effect since January 1, 2022, you cannot balance-bill a patient with group or individual coverage for emergency services, non-emergency services from an out-of-network provider at an in-network facility, or out-of-network air ambulance services.12Office of the Law Revision Counsel. 42 US Code 300gg-111 – Preventing Surprise Medical Bills The patient’s cost-sharing is capped at the in-network amount, and any remaining dispute with the plan goes to an independent dispute resolution process.13Centers for Medicare & Medicaid Services. Overview of Rules and Fact Sheets
For uninsured and self-pay patients, you must issue a Good Faith Estimate of expected charges. The timing depends on the visit:
- Service scheduled at least 3 business days out: estimate delivered within 1 business day of scheduling.
- Service scheduled at least 10 business days out: estimate delivered within 3 business days of scheduling.
- Patient requests an estimate: delivered within 3 business days of the request.
The estimate itemizes expected services, applicable diagnosis and service codes, expected charges, and the NPI and TIN for every provider involved.14eCFR. 45 CFR 149.610 – Requirements for Provision of Good Faith Estimates If the scope of care changes, send an updated estimate at least 1 business day before the service.
Stay Out of Fraud Territory
Billing errors can cross into federal fraud faster than most providers realize, and unintentional mistakes are not always a defense. Three statutes shape how every billing decision should look.
The False Claims Act makes it illegal to submit claims to Medicare or Medicaid that you know or should know are false. Penalties include treble damages plus per-claim penalties that add up quickly across hundreds of claims.15Office of Inspector General. Fraud and Abuse Laws The two most common billing patterns that trigger FCA liability are upcoding, which is billing a higher-level service than what was actually provided, and unbundling, which is billing separately for services that belong under a single bundled code. The 60-day rule matters here too: if you identify a Medicare or Medicaid overpayment and fail to return it within 60 days, it can be treated as a false claim.
The Anti-Kickback Statute makes it a felony to knowingly offer, pay, solicit, or receive anything of value to induce referrals for services payable by a federal healthcare program. Violations carry fines up to $100,000 and up to 10 years in prison, and any claim resulting from a kickback arrangement is automatically a false claim.16Office of the Law Revision Counsel. 42 USC 1320a-7b – Criminal Penalties for Acts Involving Federal Health Care Programs Free rent, below-market leases, and inflated medical directorship pay can all qualify as illegal remuneration.
The Stark Law prohibits physicians from referring Medicare or Medicaid patients for designated health services to entities where the physician or an immediate family member has a financial relationship, unless a specific exception applies. Designated health services include clinical lab work, imaging, physical therapy, durable medical equipment, home health, and hospital services. Claims from improperly referred services aren’t payable, and the billing entity faces refund obligations and penalties.17Centers for Medicare & Medicaid Services. Physician Self-Referral
A single billing pattern can trigger all three statutes at once. Regular coding audits, staff training, and written compliance policies cost far less than responding to an OIG investigation.
Keep Records and Protect PHI
Medicare requires providers to keep medical records for seven years from the date of service.18Centers for Medicare & Medicaid Services. Medical Record Maintenance and Access Requirements Some states require longer, so follow whichever period is longer. Retention covers everything supporting your claims: medical records, billing statements, insurance correspondence, remittance advices, and authorization records. Given the six-year Medicare recoupment lookback, thin documentation from years ago can cost you real money in an audit.
Billing involves protected health information, so every part of the process has to comply with HIPAA. The Security Rule requires administrative, physical, and technical safeguards for electronic PHI, including access controls that limit who can see billing data, encryption for electronic records, and transmission security for anything sent over a network.19HHS.gov. Summary of the HIPAA Security Rule Anyone with access to your billing system needs documented training, and your practice should have a written policy on how PHI moves through the billing cycle. HIPAA penalties scale with culpability, from modest fines for unknowing violations up to penalties over $2 million per year for willful neglect left uncorrected.