7 Medical Billing Mistakes That Are Costing Your Practice  

Key Takeaways 

• Most medical billing mistakes start before a claim is ever coded, at registration, eligibility checks, and charge entry. 

• In Experian Health’s 2025 State of Claims survey, 41 percent of providers said at least one in ten of their claims gets denied, up from 30 percent in 2022. 

• Missing or inaccurate claim data was the top denial driver, named by 50 percent of respondents, followed by authorizations at 35 percent and registration errors at 32 percent. 

• MGMA has long put the cost of reworking a single denied claim at roughly $25, before you count the weeks of delayed payment. 

• Medicare’s timely filing limit is 12 months from the date of service, and many commercial payers allow far less. 

• A denial log sorted by root cause and a monthly billing audit catch repeat errors faster than any one-time cleanup project. 

Medical billing problems don’t often seem costly when they happen. A member ID with digits reversed. An established patient visit marked one level low because physicians ran behind. A refusal that falls into a work queue on a busy Thursday and is never handled again. Neither of them seems like a disaster. Add them up over a month of patient visits, and they silently eat away at what a practice collects.  

Below are the seven common medical billing mistakes we see most often, what each one costs, and how to stop it from happening again. 

How Medical Billing Mistakes Affect Practice  

Billing mistakes cost money in three different ways, and only one is clear.  

The denial is clear. If the payer turns down the claim, someone needs to figure out why, fix it, and send it again. According to a long-standing MGMA standard, that extra work costs about $25 per claim in staff time. Experian found that 90% of rejections are reviewed by a person before they are sent again. You won’t receive the money you earned for a few more weeks. 

The second is being paid too little. A code is too low for the visit, there’s no modifier, or the contract rate is one the payer won’t honor. The claim is paid, there is no mistake message, and the difference just doesn’t show up. This kind of mistake is the most dangerous because it never calls your attention. 

The third is the tax break. Some denials are too old for the payer to appeal. Some claims aren’t filed on time. That means no more money comes in, and the patient usually can’t be charged for it either. 

All of these are worse when there is a lack of staff. In the same Experian poll, 43% of providers said they didn’t have enough staff, and 68% said it was harder to make clean reports than it was a year ago. 

Incomplete or Incorrect Patient Information

The most common reason a claim is rejected is bad demographic information, which you can easily avoid for very little cost. In Experian’s survey, 32% of respondents said incomplete or incorrect registration data was the main reason for denial. 

Small mistakes happen all the time. It was written down as “Bill” when the patient’s insurance card says “William.” The month and day of birth were mixed up. A subscriber named the patient, but the coverage goes through their spouse. A back-up plan no one asked about turns into a coordination-of-benefits denial three weeks later. 

The boring thing that fixes it is the reason why it works. Scan the ID and insurance card every time, not just the first time. Ask returning patients to confirm their address, employer, and insurance coverage out loud at check-in. Name on the claim must match the name on the card, letter for letter. Fewer front-end rejections happen in the first month for practices that use registration as a quality checkpoint instead of a clipboard task. 

Incorrect Medical Coding

Two kinds of medical coding mistakes cost money.  

The quiet one is undercoding. When the 2021 office visit guidelines changed, doctors selected the E/M values for 99202 through 99215 based on the total time spent on the service date. As long as providers code out of habit or because they feel safe, they lose money every time. No one says no to a claim because it is too cheap.  

Overcoding carries a different risk. If you bill a level higher than the note supports, the buyer may pay today and get the money back tomorrow after auditing the claim. This can happen for a whole group of claims. 

Then there are the technical mistakes, like not including modifier 25 on a procedure and visit that happen on the same day, codes that don’t work with the National Correct Coding Initiative, or an ICD-10 code that isn’t specific enough to show medical necessity. Code sets also change. New ICD-10-CM numbers for FY 2027 went into effect on October 1, 2026, and new CPT codes come out every January. A method that still uses last year’s billing is causing claims to be wrong before anyone even reviews them. 

The key is to check medical codes regularly and give doctors comments instead of just making changes without telling them. 

Missing Insurance Verification

A person who had insurance in March might not have insurance in October. Open enrollment is when employer plans change. Medicaid eligibility is checked again. People on Original Medicare can switch to a Medicare Advantage plan without telling the front desk. 

Authorizations belong to the same group. Experian respondents ranked authorization issues as the second most common reason for rejection (35%). Imaging, some treatments, expert recommendations, and a lot of drugs need to be approved before they can be given, and it’s not always possible to get permission after the fact. 

Avoiding Medical Billing Mistakes at the Front Desk 

A step of proof should be built into the scheduling process, not added on top of check-in. Real-time qualifying checks should be done two or three working days before the meeting and again on the day of service for expensive calls. This way, you can find out whether the service needs prior permission while you still have time to ask for it. Keep track of the reference number. That note is your proof if a payer later says the patient wasn’t eligible. 

Delayed Claim Submission

Every day a claim isn’t billed costs you cash flow. Some delays lead to losses you can’t recover. 

Providers have one year from the date of service to file with Medicare. Most of the time, commercial payers are stricter, and many contracts set limits of 90 or 180 days. Each state has its own Medicaid limits. It’s usually a waste of time and money to try to appeal a claim that doesn’t pass any of these tests. 

Watch charge lag, which is the number of days between the visit and when the claim is sent in. Choose a goal. Many practices try to send claims within a few days of the meeting. Also, check the clearinghouse rejection reports every day, because a buyer never gets a denied claim. 

Failing to Follow Up on Denied Claims

A denial isn’t a final answer. Too many practices treat it like one.  

AAFP and MGMA have used industry research for years to show that many denied claims are never reviewed again. Some of that is because of limited capacity. Some of it is a matter of priority: rejection for small amounts of bills doesn’t seem worth the time, so they keep coming in until the appeals window closes. A first-level Medicare appeal, called a redetermination, must be filed within 120 days of the initial determination. Commercial windows can change.  

Sorting is the first step to fixing it. Every rejection has a reason, like “eligibility,” “authorization,” “coding,” “documentation,” or “timely filing.” Review the log once a week. First, fix the claim in front of you, then fix the bad habit that led to it. If 40% of last month’s rejections were due to missing authorizations, that’s a front-desk process problem, not a billing problem.  

When you reprocess claims on time and handle denials consistently, you recover what would have been lost. 

Poor Accounts Receivable Management

Accounts receivable tells you how much you’ve earned but haven’t collected. Left alone, it gets harder to collect every month. 

A lot of people make the same mistakes: no one is responsible for following up on arrears; age reports are pulled but not worked on, and underpayments are marked as paid without anyone checking them against the agreed upon rate. Balances of patients also sway. A statement sent out 60 days after the visit gets fewer and slower responses than one sent out in the same week. 

Every week, take a look at your old buckets. Keep an eye on the amount of AR that has been sitting for more than 90 days, and figure out why each big one is there. At least every three months, compare your top payers’ payments to your fee schedules. Underpayments of a few dollars per claim don’t seem important, but they add up to a real number every year for a code that gets a lot of claims. 

Lack of Regular Billing Audits

Without checks, every mistake listed above can happen again and again. Each mistake is so small that no one notices it.  

The General Compliance Program Guidance from the HHS Office of Inspector General says that auditing and monitoring are important parts of a good compliance program. That is the reason for obedience. Audits can reveal trends, like a provider whose E/M distribution is much lower than their peers, a payer quietly underpaying a popular code, or a modifier the team forgets all the time.  

Checks don’t have to be very big. You can find most problems by comparing 10 to 20 claims from each source every month with the supporting documents. An outside review once a year gives a second opinion that the company’s own employees, who are often too close to the process, can’t give on their own. 

Seeing these mistakes in your own numbers?  

Credex Healthcare can review your claims, find where is being lost due to billing mistakes, rejected claims, or slow payouts, and fix the process causing it. Ask for a review of your bills. 

How to Prevent Medical Billing Mistakes 

To avoid problems, find issues early, when they are easiest and least expensive to fix.  

At registration, confirm your name, coverage, and additional insurance every time you visit. When making plans, check qualifying and prior-authorization rules early so you can follow them. When you enter a charge, make sure that the paperwork, coding, and modifiers are all in sync. Every October and January, you should also change your code sets. Use claim scrubber edits that match your actual payer rules, not just the clearinghouse defaults, before you send the claim. 

After submission, work is rejected daily and denied weekly, based on the root cause. Once a week, look over AR aging. Every month, check a sample of claims. And make sure the loop is closed: if a rejection shows a lack of training, train the person who made the mistake as well as the biller who fixed it.  

This doesn’t need any fancy software. It needs to be owned. Each step should have a named person in charge and a number they need to watch. 

What This Looks Like Inside a Real Practice 

Here’s a made-up example based on trends that keep show up. Every month, about 2,000 people go to a family practice with four providers. Its denial rate has risen above 10%, and the office manager blames payers. 

A study after two weeks shows a different picture. Almost half of the rejections are due to patients whose plans changed in January and were never checked again. Another part comes from not including modifier 25 for visits where the provider also injected something or took off a skin spot. One provider’s regular visits are mostly at level 3, even though the notes often support level 4.  

None of those issues are payer issues. Pre-visit qualifying checks are now done, a modifier 25 note is built into charge review, and the writer meets with the provider for an hour to give comments on the paperwork. In just two billing cycles, eligibility denials drop sharply, and average reimbursement per visit goes up without adding a single appointment. 

In general, it looks like that. It’s not often that fighting payers harder leads to the most progress. They come from getting rid of the few habits that lead to mistakes in the first place. 

When Should You Consider Outsourcing Medical Billing? 

Not every practice needs to outsource. An in-house team might be a good idea if your denial rate is low, your accounts receivable is current, and your billing staff is stable and well-trained. 

It’s pretty easy to tell when it’s time to look into professional medical billing services. No one has time to look into why your rejection rate keeps going up. Every three months, AR after 90 days goes up. You’d be in trouble if someone who knew everything about bills left. The team already there gets stretched thin as you add more providers or locations. Or, your code hasn’t been checked by anyone in over a year.  

A good billing partner does more than just send in claims. Seek proofreading and coding checks before sending, follow up on denials within a set timeframe, work weekly on accounts receivable, and receive monthly reports that show denials by reason, not just the total amount collected. Expect clear answers when you ask them how they would handle the mistakes on this list. A good partner for cycle management can also do a billing audit before they start working with you, so you know where you stand from the start. 

Frequently Asked Questions 

What is the most common medical billing mistake?  

Claim data, such as patient demographics and insurance information, is missing or incorrect. Experian found this was the main reason for denial in 2025. 

How much does a denied claim cost to fix?  

Based on MGMA’s standard, rework costs about $25 per claim, not including the time it takes to get paid. 

How long do I have to submit a Medicare claim?  

Twelve months after the service date. Most of the time, commercial and Medicaid deadlines are shorter. 

Can a practice bill the patient if a claim misses timely filing?  

Not often. A lot of customer arrangements treat it as a cost the provider can write off. 

How often should a practice audit its billing?  

Most practices do well with a small internal group every month and an external review once a year. 

Do billing mistakes affect compliance as well?  

Yes. Overcoding or submitting claims without proper documentation can cause payers to demand reimbursement and expose you to audits. 

The Bottom Line on Medical Billing Mistakes 

It’s easy to see why medical billing mistakes happen, which is good news. There are known ways to fix mistakes in patient data, missing codes, skipped qualifying checks, late claims, ignored rejections, ignored AR, and missing reports. When it comes to collecting, the best practices aren’t the ones that never go wrong. They catch mistakes early and make sure they don’t happen again.