2026-04-10 · health, claims, guide

Health Insurance Claims Step-by-Step

Key Takeaways

Most health insurance claims are filed automatically by your provider, but you may need to file one yourself for out-of-network or out-of-country care.
An Explanation of Benefits (EOB) is not a bill. Learn to read it before paying anything.
If a claim is denied, you have the right to appeal, first internally and then through an independent external review.
The No Surprises Act protects you from most surprise bills for emergency services and out-of-network care at in-network facilities.

Overview

Most health insurance claims are filed by your provider automatically. You receive an Explanation of Benefits, pay your share, and the process is done. This guide covers what to do when something goes wrong: unexpected denials, out-of-network bills, or claims you need to file yourself. Whether you are dealing with a health insurance claim denied or a surprise medical bill, the steps below will help you take action.

How Health Insurance Claims Work

When you visit a doctor, hospital, or other provider, the billing process typically follows four steps:

Your provider submits a claim to your insurance company with procedure codes and diagnosis codes.
Your insurer processes the claim against your plan’s benefits, checking whether the service is covered, whether you met your deductible, and whether prior authorization was required.
You receive an Explanation of Benefits (EOB) showing what the provider billed, what the plan paid, and what you owe.
You pay your remaining balance (deductible, copay, or coinsurance) to the provider.

An EOB is not a bill. It is a summary of how the claim was processed. Wait for the actual bill from your provider before paying.

How to Read Your Explanation of Benefits (EOB)

Your EOB contains several key fields. Understanding each one helps you spot errors before they become costly:

Billed amount: the total your provider charged for the service.
Allowed amount: the maximum your insurer has agreed to pay for that service under your plan’s negotiated rate.
Plan paid: the portion your insurer covered after applying your cost-sharing.
Your responsibility: the amount you owe, broken into deductible, copay, and coinsurance.
Reason codes: short codes explaining why your plan paid the amount it did, or why a charge was reduced or denied.

If the allowed amount is much lower than the billed amount, that is typically normal for in-network care. For out-of-network care, you may owe the difference (called balance billing), unless the No Surprises Act applies.

Compare every EOB to the bill you receive from your provider. If the numbers do not match, call your insurer and your provider before paying. Understanding your coverage levels makes it easier to verify whether the EOB matches your plan.

When You Need to File a Claim Yourself

In most situations, your provider handles the claim. However, you may need to file one yourself in these cases:

Out-of-network provider who did not bill your insurer directly.
Out-of-country medical care where foreign providers do not submit claims to U.S. insurers.
You paid upfront and need reimbursement from your plan.

Steps to file a claim yourself

Get an itemized bill from your provider showing procedure codes, dates of service, and charges.
Download your insurer’s claim form from their website or request one by phone.
Complete the form with your policy number, provider details, and a description of the service.
Attach the itemized bill, receipts, and any supporting documentation (referral letters, pre-authorization numbers).
Submit the form by mail, fax, or through your insurer’s online portal.
Keep copies of everything you send and note the date of submission.
Follow up within 30 days if you have not received a response.

Your insurer is required to process claims within the timeframe specified by your state’s regulations, typically 30 to 45 days.

What to Do When a Claim Is Denied

A health insurance claim denied notice can be stressful, but a denial is not always the final answer. Start by reading the denial letter carefully. It must include the specific reason your claim was denied and instructions for how to appeal.

Common reasons for claim denials

Service not covered under your plan’s benefits.
Prior authorization was not obtained before the procedure.
Out-of-network provider not covered at the billed level.
Coding error where the wrong procedure or diagnosis code was submitted.
Duplicate claim that the insurer believes was already processed.
Timely filing deadline missed by the provider.

Steps to take after a denial

Call your insurer’s customer service number and ask for a detailed explanation of the denial. Note the representative’s name and reference number.
Contact your provider’s billing office. If the denial was due to a coding error, the provider can correct and resubmit the claim at no cost to you.
Check whether the service requires prior authorization and whether it can be obtained retroactively.
If the denial stands after these steps, file a formal appeal.

For a broader overview of the appeals process across all insurance types, see the claims denial and appeals guide.

How to Appeal a Denied Health Insurance Claim

Federal law gives you the right to appeal any health insurance claim denial. The process has two stages.

Internal appeal

Your first step is an internal appeal filed with your insurance company.

Write a formal appeal letter stating why the claim should be covered. Reference your plan’s benefits, the specific service, and any medical necessity.
Include supporting documents: medical records, your doctor’s letter of medical necessity, clinical guidelines supporting the treatment, and a copy of the denial letter.
Submit the appeal within the deadline stated in your denial letter (typically 180 days from the denial date).
Your insurer must respond within 30 days for pre-service claims or 60 days for post-service claims.

External review

If your internal appeal is denied, you can request an external review by an independent third party that has no connection to your insurer.

File the request within four months of receiving the internal appeal denial.
The external reviewer examines the clinical evidence and makes a binding decision.
External review decisions are typically issued within 45 to 60 days.
If the reviewer rules in your favor, your insurer must cover the claim.

Your state’s Department of Insurance can help you navigate the external review process and may have an expedited review option for urgent situations.

Tips for a stronger appeal

Ask your doctor to write a letter explaining why the treatment was medically necessary.
Include peer-reviewed studies or clinical guidelines that support the treatment.
Keep copies of every document you submit and every response you receive.
If your health insurance plan type is self-funded (common with large employers), the appeal may be governed by federal ERISA rules rather than state law.

Handling Surprise Medical Bills

A surprise medical bill, sometimes called a balance bill, happens when you receive care from an out-of-network provider you did not choose, often at an in-network facility.

What the No Surprises Act covers

The No Surprises Act, effective January 2022, protects patients from surprise bills in these situations:

Emergency services at any facility, regardless of network status.
Out-of-network providers at in-network facilities (such as an anesthesiologist or radiologist you did not select).
Air ambulance services from out-of-network providers.

In these cases, you pay only your in-network cost-sharing amount (copay, coinsurance, deductible). The provider and insurer resolve the remaining balance between themselves.

What the No Surprises Act does not cover

Non-emergency care at out-of-network facilities where you knowingly chose an out-of-network provider.
Ground ambulance services (not included in the current law).
Services where you signed a written consent to waive your protections and agree to out-of-network rates before receiving care.

How to dispute a surprise bill

Compare the bill to your EOB. If the bill exceeds your in-network cost-sharing for a covered situation, it may violate the No Surprises Act.
Contact your insurer and ask them to reprocess the claim under the No Surprises Act protections.
File a complaint with your state’s Department of Insurance if the provider or insurer does not comply.
You can also call the federal No Surprises Help Desk at 1-800-985-3059 for assistance.

Understanding how health insurance networks work can help you avoid out-of-network situations in the future.

Frequently Asked Questions

What is the difference between a claim denial and a claim rejection? A rejection means the claim was not processed at all, usually because of missing or incorrect information (wrong policy number, incomplete form). A denial means the claim was processed but the insurer decided not to pay. Rejections can usually be fixed and resubmitted. Denials require a formal appeal.

How long do I have to appeal a denied claim? Most plans allow 180 days from the date of the denial letter to file an internal appeal. Check your denial notice for the exact deadline. External review requests are typically due within four months of the internal appeal decision.

Can my doctor help with the appeal? Yes. A letter of medical necessity from your treating physician is one of the most effective pieces of evidence in an appeal. Ask your doctor to explain why the treatment was needed and cite relevant clinical guidelines.

What if I already paid a bill that should have been covered? You can still file a claim or appeal. If the insurer determines the service should have been covered, you are entitled to reimbursement. Keep all receipts and proof of payment.

Does the No Surprises Act apply to all health plans? It applies to most private health plans, including employer-sponsored and marketplace plans. It does not apply to people who are uninsured or covered by federal programs like Medicare or Medicaid (which have their own protections).

Next Steps

Review the claims denial and appeals guide for detailed appeal letter templates and escalation paths.
Visit the health coverage hub for a complete overview of health insurance topics.
Learn how provider networks affect your costs in the health insurance networks guide.
Understand your plan’s cost structure with the health insurance cost guide.
Make sure your plan matches your needs by reviewing how to choose coverage levels.

Sources and References

Centers for Medicare & Medicaid Services (CMS.gov): “How to appeal a health insurance company decision” and “External review process.”
U.S. Department of Labor: “Filing an appeal of a health plan decision” under ERISA-governed plans.
Centers for Medicare & Medicaid Services: No Surprises Act implementation guidance and consumer protections (effective January 1, 2022).
National Association of Insurance Commissioners (NAIC): State-by-state external review requirements and consumer complaint resources.
State Departments of Insurance: Contact your state’s DOI for filing complaints and requesting external review assistance.