How to Check Your Medical Bill for Errors (Step-by-Step)

Up to 80% of medical bills contain at least one error, according to Medical Billing Advocates of America. These aren’t small rounding issues. Duplicate charges, wrong procedure codes, and fees for services that never happened can add hundreds or thousands of dollars to your bill. Here’s how to catch them.

I started building Elena after hearing the same pattern repeat across dozens of conversations: someone gets a bill, pays it because it looks official, and never realizes they were overcharged. One person I spoke to had a $6,200 ER bill with three duplicate line items and a charge for a procedure room she never entered. That’s $1,400 she would have just... paid.

You don’t need special software to catch most errors. You need an itemized bill, 30 minutes, and the steps below.

What kinds of errors show up on medical bills?

Before you start checking, it helps to know what you’re looking for. These are the most common billing errors, ranked by how often they appear:

Step 1: Request an itemized bill

The summary bill you get in the mail is almost useless for error-checking. It might say “Emergency Services - $4,800” with no detail on what that includes. You need the itemized statement that lists every individual charge with its CPT (Current Procedural Terminology) code.

Call the billing department and say: “I’d like a fully itemized bill with CPT codes for all charges.” They’re required to provide this. Under the No Surprises Act (effective January 2022), you have the right to receive a detailed bill within 30 days of request.

Step 2: Check for duplicate charges

This is the easiest error to spot. Scan every line and look for the same CPT code appearing more than once on the same date of service. Common duplicates include:

• Lab tests (blood panels, urinalysis) billed twice
• Imaging (X-rays, CT scans) listed on two separate line items
• IV administration fees charged per-bag when it should be a single charge
• Room fees listed for multiple rooms on the same day

Step 3: Verify the procedure codes

Every charge on your bill corresponds to a CPT code. You can look up any code on the AMA’s CPT code lookup tool or a free site like FindACode.com. Check that the code matches what actually happened during your visit.

For example: CPT 99285 is the highest-level ER evaluation code, billed at $500-$1,500+ depending on the hospital. If you went to the ER for a sprained ankle and were seen for 15 minutes, you probably should have been billed 99283 (moderate complexity), not 99285 (high complexity). This is called upcoding, and it’s one of the most common billing errors.

Step 4: Compare against your EOB

Your insurance company sends an Explanation of Benefits (EOB) after processing a claim. The EOB shows what the provider billed, what your insurance approved, and what you owe. Compare this line-by-line against your itemized bill.

Things to watch for:

• The provider billing you for more than the “patient responsibility” amount on the EOB
• Charges on your bill that don’t appear on the EOB at all (meaning they were never submitted to insurance)
• Denied charges that the provider is billing you for directly, which may be appealable

Step 5: Check for unbundling

Some procedures are supposed to be billed together as a single “bundled” code. When a hospital splits them into separate charges, it’s called unbundling, and it inflates the total.

A common example: a basic metabolic panel (BMP) is a single lab test that measures 8 things (sodium, potassium, glucose, etc.). The bundled CPT code is 80048 and costs $15-$40. If a hospital bills each of those 8 tests separately, the total can be $200-$400 for the same blood draw.

You can check for unbundling by looking for clusters of related lab or procedure codes on the same date. If you see 5-8 individual lab codes, search whether they should have been billed as a panel.

Step 6: Look up fair prices for each charge

Even if your bill has no outright errors, you might be overpaying relative to what the procedure should cost. Two ways to check:

1. Medicare rates: Search any CPT code on Medicare.gov’s Physician Fee Schedule to see what Medicare pays. Hospital charges are often 2-5x the Medicare rate. If your bill is 10x or more, that’s worth questioning.
2. Hospital price transparency files: Since January 2021, the CMS Hospital Price Transparency Rule requires every hospital to publish their actual negotiated rates. These are public files you can download from the hospital’s website (look for “price transparency” or “machine-readable files”). They’re massive spreadsheets, but if you search for your CPT code, you can see the exact rate your insurer negotiated.

Step 7: Dispute the errors in writing

Once you’ve found errors, don’t just call. Send a written dispute letter to the billing department. Include:

1. Your name, account number, and date of service
2. Each specific error with the line item, CPT code, and charged amount
3. What the correct charge should be, with your reasoning
4. A request for an adjusted bill within 30 days
5. A note that you are requesting investigation under applicable state and federal billing regulations

Send it certified mail so you have proof of delivery. Many billing departments will correct obvious errors (duplicates, wrong codes) within one billing cycle. For larger disputes, you may need to escalate to your state’s insurance commissioner or file a complaint with CMS.

What about charity care and financial assistance?

If your bill is simply too large even without errors, most nonprofit hospitals are required to offer financial assistance under IRS Section 501(r). This applies to any hospital with tax-exempt status, which includes most major hospital systems. You can qualify for partial or full write-offs based on income, even if you have insurance.

Ask the billing department for their “financial assistance policy” or “charity care application.” The income thresholds vary, but many hospitals offer discounts for households earning up to 400% of the Federal Poverty Level.

Have you ever caught an error on a medical bill?

I hear about these every week from people testing Elena. The most common reaction: “I never would have caught that.” If you’ve found an error on a bill, or if you’ve tried disputing one and hit a wall, I’d genuinely like to hear about it. These stories are what shape what we build.