Is CO-45 a bad thing to see on my medical bill?

No, it's usually a good thing. CO-45 means your provider charged more than your insurer allows, and that extra amount is typically written off. This means you usually don't have to pay that specific portion of the bill.

What is a 'fee schedule'?

A fee schedule is a list of prices that your insurance company and your healthcare provider have agreed upon for various medical services. It's the maximum amount your insurer will pay for each service, and what the provider agrees to accept.

Who pays the difference when a charge exceeds the fee schedule?

Typically, neither you nor your insurance company pays the difference. The healthcare provider 'writes off' this excess amount. This means they agree not to collect that money from you or your insurer, as part of their contract.

Should I call my provider or insurance company first if I see CO-45?

Start by reviewing your Explanation of Benefits (EOB) carefully. If it clearly shows the amount was written off and your patient responsibility is correct, you might not need to call anyone. If you're still confused or concerned, call your provider's billing office first to confirm the write-off.

Can a provider bill me for the CO-45 amount later?

Generally, no. When a provider has a contract with your insurer, they agree to accept the allowed amount as full payment (minus your deductibles, copays, or coinsurance). They are usually not allowed to 'balance bill' you for the amount written off due to CO-45.

Billing Adjustment

What does denial code CO-45 mean on my medical bill?

Claim Adjustment Reason Code (CARC) CO-45 means your healthcare provider charged more for a service than your insurance company has agreed to pay. This is usually an adjustment, not a denial that leaves you owing money. The extra amount is typically 'written off' by the provider.

By the ExplainMyBill.ai Editorial Team · Reviewed by our billing research team

Published June 5, 2026 · Updated June 5, 2026

What 'Charge Exceeds Fee Schedule' (CO-45) Really Means

When you see CO-45 on your Explanation of Benefits (EOB), it tells you that your provider's bill for a service was higher than the amount your insurance plan allows. Think of it like this: your insurance company and the provider have a special agreement. This agreement includes a 'fee schedule,' which is a list of pre-set prices for different medical services.

CO-45 simply means the provider billed more than that agreed-upon price for a specific service. It doesn't mean the service wasn't needed or performed. It's about the cost.

Why Your Insurer Applies This Code

Insurance companies apply CO-45 because they have a contract with your healthcare provider. This contract sets the maximum amount the insurer will pay for a particular service. If a provider bills more than that maximum, the insurer will only pay up to the agreed amount.

The CO-45 code is used to explain why the amount paid by the insurer (and your potential share) is based on the lower, agreed-upon fee, not the higher amount originally billed by the provider. It's a way for your insurer to enforce their contract.

Does CO-45 Mean You Owe Money?

In most cases, when you see CO-45, it's good news for you. It typically means the extra amount billed by the provider (the part that 'exceeds the fee schedule') is 'written off.' A write-off means the provider agrees not to charge you for that difference.

So, you generally do not owe the amount that was written off due to CO-45. Your responsibility is usually limited to your deductible, copay, or coinsurance based on the *allowed* amount, not the original, higher billed amount.

What to Look For on Your Explanation of Benefits (EOB)

Your EOB is key to understanding CO-45. Here's what to check:

Look for the specific service line where CO-45 appears. You should see the 'billed amount' from the provider, the 'allowed amount' (what your insurer agreed to pay), and the 'difference' or 'adjustment' that was written off.

Pay close attention to the column labeled 'patient responsibility' or 'what you owe.' For the portion of the bill related to CO-45, this column should typically show zero. If it shows an amount you're expected to pay for the 'exceeded' portion, that's a red flag.

Next Steps: Confirming Your Bill

If your EOB clearly shows that the amount exceeding the fee schedule was written off and your patient responsibility is correct, you likely don't need to do anything further for that specific adjustment. However, if you're still unsure or if your EOB indicates you owe the excess amount, here's what to do:

First, call your healthcare provider's billing office. Ask them to confirm that the amount exceeding the fee schedule (the CO-45 adjustment) has been written off and that you are not responsible for it. You can say: 'I received an EOB with code CO-45. It says 'Charge Exceeds Fee Schedule.' Can you please confirm that the difference between your billed amount and my insurance's allowed amount has been written off and I don't owe that portion?'

If the provider's office says you do owe the amount, or if you get conflicting information, then call your insurance company. Ask them to explain the CO-45 adjustment and confirm your patient responsibility based on their contract with the provider.

When to Consider an Appeal

An appeal is generally not needed for CO-45 itself, because it's usually an adjustment in your favor. However, if your provider tries to bill you for the amount that was written off, or if you believe the 'allowed amount' from your insurance is incorrect for a service that should have been covered differently, you might consider an appeal.

An appeal would be directed at your insurance company if you think they didn't apply the correct allowed amount, or if they are asking you to pay for something that should have been a provider write-off. Always start with a clear understanding from both your provider and insurer before considering an appeal.

Frequently asked questions

Is CO-45 a bad thing to see on my medical bill?: No, it's usually a good thing. CO-45 means your provider charged more than your insurer allows, and that extra amount is typically written off. This means you usually don't have to pay that specific portion of the bill.
What is a 'fee schedule'?: A fee schedule is a list of prices that your insurance company and your healthcare provider have agreed upon for various medical services. It's the maximum amount your insurer will pay for each service, and what the provider agrees to accept.
Who pays the difference when a charge exceeds the fee schedule?: Typically, neither you nor your insurance company pays the difference. The healthcare provider 'writes off' this excess amount. This means they agree not to collect that money from you or your insurer, as part of their contract.
Should I call my provider or insurance company first if I see CO-45?: Start by reviewing your Explanation of Benefits (EOB) carefully. If it clearly shows the amount was written off and your patient responsibility is correct, you might not need to call anyone. If you're still confused or concerned, call your provider's billing office first to confirm the write-off.
Can a provider bill me for the CO-45 amount later?: Generally, no. When a provider has a contract with your insurer, they agree to accept the allowed amount as full payment (minus your deductibles, copays, or coinsurance). They are usually not allowed to 'balance bill' you for the amount written off due to CO-45.

This article is educational information, not medical, legal, or financial advice. Billing rules change and individual situations vary — always confirm details with your provider or insurer.