Medical bill mistakes and errors: common kinds and how to check your bill

What surveys say about mistakes on medical bills

We found no reliable count of how many bills contain mistakes. Surveys measure what people noticed: in a 2022 KFF survey, 43% of US adults said they had received a medical or dental bill in the past five years that they thought contained an error. Of insured adults who challenged a bill they thought their insurance should have covered, 38% said it was reduced or eliminated (Commonwealth Fund, 2024). Claims that eight or nine in ten bills contain errors are widely repeated, but we found no published study behind them. More in how common medical billing errors really are.

How to check your medical bill for mistakes, step by step

1. Get the itemized bill. CMS's first step is to “Ask your provider’s billing department for a detailed bill.” Our free itemized bill letter writes the request.
2. Find the EOB for the same date of service. If the bill came first, ask whether the claim was sent to your insurer.
3. Match each line with the EOB: date, code or description, amount billed, amount allowed, plan paid and your share. CMS says to “Make sure the ‘your share’ amount is the same as what’s on your bill.”
4. Check the math: quantity times unit price, the lines against the total, and the total minus payments and adjustments against the amount due.
5. Check dates, quantities and codes against what happened, and ask the billing office to describe any line in plain words.
6. Compare with your records. Your right to a copy of your health information covers “medical records and billing records” (45 CFR 164.524 and 164.501). HHS says the provider normally has up to 30 days, and that “you can’t be denied access for not paying your medical bill.”
7. List each line to ask about with its page and line number.

For the same checks as a ten-point list to keep next to the bill, with extra checks after a hospital stay, use the medical bill checklist.

What not to assume

A line that looks odd may have an ordinary explanation.

• Two similar lines can be two services.
• A high price is not an error by itself. If you cannot pay it, ask about financial assistance.
• An unfamiliar code is not proof.
• An insurer payment does not confirm every line, and a line the insurer did not pay is worth a question before you pay it yourself.

What to do if you think your bill has a mistake

Call the billing number on the statement about specific lines, not the whole bill:

"I'm calling about my statement dated [date], account [number]. I have a question about line [number]. Can you tell me what it covers and how it was calculated?"

Note the date, who you spoke to and what they said. If a line changes, ask for a corrected statement before you pay. If the question is how insurance processed the claim, call the number on your insurance card: CMS says your insurer “might be able to fix billing errors with your health care provider.” For outside help, try your state's Consumer Assistance Program, if your state has one, or the No Surprises Help Desk at 1-800-985-3059.

If a call does not settle it, write. Our free dispute letter asks about each charge you list, and the refund request letter covers money you already paid. Next steps are in how to dispute a medical bill and if the billing office says no.

Deadlines to know:

• Insurance appeal: for a job-based or Marketplace plan, within 180 days (6 months) of receiving notice that the claim was denied (HealthCare.gov). Medicare and Medicaid have shorter deadlines: your denial notice gives yours, and with Original Medicare it is the date on your Medicare Summary Notice.
• A bill at least $400 above one provider's good faith estimate, if you had no insurance or told the provider you would not use it: the federal dispute needs a first bill dated within the last 120 calendar days and has a $25 non-refundable fee (CMS). More in the No Surprises Act explained.
• A debt collector: its validation notice gives an end date for a 30-day period to dispute the debt in writing. If you write by that date, it must pause collecting the amount you dispute until it has answered (CFPB). Our free collection agency letter helps.

What MedBillCheckup checks, and what it cannot know

MedBillCheckup runs fixed rules, not AI. It finds lines worth asking about and never decides that a line is a mistake: only the provider or insurer can confirm one. It looks for repeated or near-identical lines, a similar charge from two providers, high quantities, totals that do not add up, an amount due that differs from the bill's patient responsibility, dates that do not fit together, routine supplies billed separately, more units than Medicare usually expects, and a few everyday medicines priced far above what pharmacies pay. With a few optional answers, such as your share from your EOB, what you paid, your yearly out-of-pocket maximum and how much had already counted toward it, it also checks whether the bill asks for more than your EOB, whether you paid more than your share and whether this bill goes past your maximum. Two short questions let it check for a possible surprise bill. It cannot know what care you got, whether a code fits that care, or how long you stayed.

Open your bill in MedBillCheckup: take a photo or choose the PDF. It is read on your device and the file stays with you (what is sent for the checks). The free check shows how many things are worth asking about and, when your answers point to money, the largest amount you may get back or may not owe. The full list is paid: each line, why it is worth asking about and the question to ask. It never says a charge is wrong; only your provider or insurer can confirm that.