Claims, reimbursement and appealing a denial

Most of the time you never file anything: the doctor bills your insurer, the insurer pays its share, and you get an Explanation of Benefits telling you what is left. This guide covers the times that does not happen — and what to do when a claim comes back refused.

Usually

The provider files; you pay only the copay or coinsurance

You file when

Out-of-network, travelling, or the provider does not bill insurers

Filing deadline

Typically 90–365 days from the date of service

Appeal deadline

Usually 180 days from the denial notice

1. The Explanation of Benefits is not a bill

After any visit your insurer sends an EOB showing what was charged, what the plan paid, the discount it negotiated, and what you owe. It looks alarmingly like an invoice and says so at the top; it is not one.

Wait for the EOB, then compare it against the bill the provider sends. Pay the provider only what the EOB says you owe. When the two disagree, one of them is wrong — see understanding and reducing a medical bill.

2. Prior authorization: get it before, never after

Scans, surgery, hospital admissions, physiotherapy and many expensive drugs need the insurer's agreement in advance. Without it the claim is refused, however medically necessary the treatment was.

The doctor's office normally requests it, but the consequence lands on you, so confirm it yourself: ask for the authorisation number and the dates it covers before the appointment.

3. When you have to claim it back yourself

You will need to file your own claim if:

• you saw an out-of-network provider on a plan that partly covers them
• you were travelling and paid a provider who does not bill your insurer
• you paid a clinic that only takes cash, and want to claim the covered portion
• you bought a prescription somewhere outside the plan's pharmacy network

Ask the provider for a superbill — an itemised receipt showing the date, the diagnosis codes (ICD), the procedure codes (CPT), the provider's tax ID and NPI number, and proof that you paid. A claim without codes will be refused for missing information.

Then download your insurer's claim form, attach the superbill and the receipt, and send it before the filing deadline. Keep a copy of everything you send.

4. If a claim is denied

Around one in five claims is refused, and a large share of the refusals that get appealed are overturned. Very few people appeal. That gap is worth money.

Read the denial reason first. Most fall into four groups, and only one of them is a real dispute:

Reason	What to do
Coding or clerical error	Ask the provider's billing office to correct and resubmit. Not an appeal at all.
Prior authorization missing	Ask the doctor to request retroactive authorisation with a letter of medical necessity.
Out of network	Check whether an in-network provider was actually available; if not, ask for a network gap exception.
Not medically necessary	This is the real fight. Appeal.

The appeal ladder:

1. Internal appeal — you have about 180 days from the denial. Put it in writing. Attach a letter of medical necessity from your doctor, the relevant clinical guidelines, and the plan's own policy document if it supports you.
2. Expedited appeal — if waiting would endanger your health, ask for this. Decisions come in days rather than weeks.
3. External review — an independent body outside the insurer reviews the case, and its decision binds the insurer. This is the step most people never reach.
4. Complain to your state insurance regulator. It is free, it is taken seriously, and regulators track patterns of refusals by insurer.

5. HSA and FSA — paying with untaxed money

Both let you pay medical costs with money that was never taxed, which is effectively a 20–35% discount on every eligible expense.

• FSA — offered by an employer. You choose an amount at the start of the year, and it is available immediately. Most of it is forfeited if unspent by year end, so estimate conservatively.
• HSA — only available with a high-deductible plan. The money is yours permanently, rolls over every year, moves with you when you change job, and can be invested.

Eligible: doctor visits, prescriptions, dental, glasses and contacts, many over-the-counter items, and — often overlooked — travel to appointments. Keep the receipts; you are not asked for them at the time, but you must be able to produce them.

6. Surprise bills

Federal law protects you from most out-of-network bills for emergency care, and from out-of-network providers treating you inside an in-network facility. If one arrives, say "No Surprises Act" to the billing department in writing, do not pay it while it is disputed, and report it to the federal helpline if it is not withdrawn.