A 2017 study by the AMA found that between 30% and 80% of US medical bills contain at least one error. The single most common error? Duplicate charges — the hospital bills you twice for the same service.
This guide walks through how to find them yourself in under two minutes, and what to do when you spot one.
What counts as a duplicate
Duplicates come in three flavors. The first is the obvious one: the same CPT code billed twice on the same date of service. CPT codes are the five-digit numbers next to each line item (e.g. 36415 for a blood draw, 80053 for a comprehensive metabolic panel).
If you see the same code listed twice with the same date, that's a flag — but not automatically wrong. Some codes can legitimately appear twice if the procedure was actually performed twice (two separate blood draws hours apart, for example).
The second is bundled-service duplicates. Some procedures already include other procedures in their fee. A "comprehensive metabolic panel" (CPT 80053) is itself a bundle of 14 individual tests — glucose, sodium, potassium, BUN, creatinine, and more. If the hospital bills you for the panel and for sodium separately, that's improper unbundling. CMS's National Correct Coding Initiative (NCCI) edits explicitly prohibit this.
The third is observation-period duplicates. When you're admitted for hospital observation (CPT G0378), most ancillary services performed during that period — IV pushes, basic monitoring, supplies — are already included in the observation rate under Medicare's Outpatient Prospective Payment System (OPPS). Charging them separately is "unbundling" and isn't allowed.
A 90-second audit you can run yourself
Pull out your itemized bill. If you only have a summary, call the billing department and ask for "itemization with CPT codes" — they're required to provide one under most state laws.
Then walk through these checks:
-
Same code, same date. Use Ctrl+F or your eyes. Note any CPT code that appears twice on the same date. Common offenders:
36415(venipuncture / blood draw),96374(IV push),99213-99215(office visit levels). -
Panel + components. Look for any of these panel codes:
80050,80053,80061,80069,80076,80048. If you see one of these alongside any of the individual component tests (82947glucose,84132potassium,84295sodium,84520BUN,82565creatinine, etc.), the components are likely already included in the panel. -
Observation + ancillaries. If you see
G0378(observation per hour) on the bill, then check whether the same date also has96374(IV push),94640(nebulizer),94760(pulse oximetry), or generic "supplies" — those are typically packaged into the observation rate. -
"Hospital services" + specific charges. If you see a vague line like "Hospital services" or "Facility fee" without a CPT code AND specific procedure codes for the same date, you may be paying twice for the same care.
What to do when you spot one
You don't have to be a billing expert to push back. Write a short letter to the hospital's billing department that includes:
- The bill date and account number
- The duplicate charge(s) you identified with their CPT codes
- A reference to the relevant rule (CMS NCCI edits for unbundling, CMS OPPS for observation packaging, or just "this is the same charge as line 7")
- A specific ask: "Please remove this charge and send a corrected bill"
You're not making a legal argument — you're flagging a billing error. Hospitals fix these all the time when patients catch them; the people who never catch them just pay.
Federal law (45 CFR § 164.524) gives you the right to a corrected statement. Most state laws (e.g. Arizona's A.R.S. § 44-1522, Virginia's § 32.1-137.07) treat persistent over-billing as a deceptive trade practice.
What if there are too many to check by hand
A real itemized bill from a hospital stay can have 30 to 150 line items. Cross-checking each one against CPT bundling rules, NCCI edits, and observation OPPS rules is genuinely too much for a single sitting.
That's what Audra is for. Upload any PDF or photo of your bill and we run every line through CMS billing rules, your state's consumer protection laws, and the No Surprises Act in about 60 seconds. We hand back a list of every issue we find plus a ready-to-send appeal letter quoting the specific rules being violated.
Your first audit is free. Run one and see what the bill is hiding.