A claim can be submitted on time, the patient can have active insurance, and the service can be medically necessary yet a medical practice may still wait weeks for payment because one detail was entered incorrectly.
That is why medical billing and coding errors deserve more attention than they often receive. A wrong patient ID, an unsupported diagnosis code, an incorrect modifier, or incomplete documentation can trigger a rejection, denial, payment delay, or additional administrative work.
For physicians and practice managers, these problems are not just billing-office issues. Repeated errors can increase accounts receivable, slow cash flow, create unnecessary staff work, and make it harder to maintain a predictable revenue cycle.
In this guide, we’ll look at common medical billing and coding errors, explain how they affect reimbursement, and discuss practical ways practices can reduce avoidable claim problems.
What Are Medical Billing and Coding Errors?
Medical billing and coding errors occur when information on a claim does not accurately represent the patient, service, diagnosis, documentation, payer requirements, or billing circumstances.
Although billing and coding are closely connected, they are not the same.
Medical coding errors generally involve the incorrect selection or reporting of diagnosis, procedure, or service codes. This can include CPT, HCPCS, ICD-10-CM codes, or modifiers.
Medical billing errors are broader and can involve patient demographics, insurance information, eligibility, claim submission, authorization, provider information, duplicate claims, or other billing details.
Both types of errors can affect how a payer processes a claim.
CMS data also demonstrates why accurate coding and documentation matter. For the 2024 Medicare reporting period, CMS reported a 10.3% improper payment rate for E/M services, with incorrect coding accounting for 49.1% of improper payments and insufficient documentation accounting for 34.1%.
These numbers are only for Medicare E/M services. They shouldn’t be taken as a general mistake rate for all medical practices and insurance companies. They do illustrate how errors in coding and documentation can lead to payment difficulties.
10 Common Medical Billing and Coding Errors
Medical billing and coding errors can happen at several points in the revenue cycle. Some begin during patient registration, while others occur during documentation, coding, claim submission, or follow-up.
Here are ten common problems practices should monitor.
1. Incorrect Patient or Insurance Information
Small registration mistakes can create major claim problems.
A patient’s name, date of birth, member ID, group number, or insurance plan may be entered incorrectly. An outdated insurance card may also remain in the system after the patient changes coverage.
For example, a patient may come in with a new insurance card during a visit, but the billing staff uses information from an older policy to file the claim. The claim can then be sent to the wrong payer or fail eligibility checks.
Practices can reduce these errors by verifying demographic and insurance information regularly rather than relying only on information collected during the patient’s first visit.
2. Incorrect CPT or HCPCS Code Selection
CPT and HCPCS codes communicate what service was performed and billed.
Selecting a code that does not accurately reflect the service can result in claim problems, underpayment, overpayment concerns, or additional review.
Coding teams should work from current coding resources and the provider’s documentation instead of selecting a code simply because it appears similar to a previous claim.
Code selection should reflect the actual service performed and the applicable payer and coding requirements.
3. Incorrect or Incomplete ICD-10-CM Coding
Diagnosis coding provides important information about why a service was performed.
An incorrect, incomplete, or insufficiently specific ICD-10-CM code may fail to support the service billed. In some situations, it can contribute to a medical necessity issue or denial.
Coders should review the provider’s documentation carefully and select the most appropriate diagnosis supported by the record.
ICD-10-CM codes and guidelines also change. CMS currently provides FY 2027 ICD-10-CM files for patient encounters from October 1, 2026, through September 30, 2027.
That makes regular coding updates and staff education important for practices that want to avoid relying on outdated code sets.
4. Missing or Incorrect Modifiers
Modifiers can provide important information about how, when, or under what circumstances a service was performed.
Using the wrong modifier—or failing to use one when documentation supports it can affect claim processing.
For example, certain coding circumstances may require a modifier to distinguish separately reportable services. However, modifiers should never be added simply to make a claim payable. The applicable coding rules and documentation must support their use.
CMS’s National Correct Coding Initiative (NCCI) includes procedure-to-procedure edits designed to prevent inappropriate payment when certain services should not be reported together. CMS updates these edit files quarterly.
5. Documentation That Does Not Support the Codes
A claim can contain technically valid codes and still face problems if the medical record does not support them. Documentation gaps are among the costliest medical billing and coding errors because the problem often isn’t visible until the claim is reviewed.
The documentation should support the services reported, including the level of service and diagnoses when applicable.
This is particularly important for evaluation and management services. CMS identifies insufficient documentation as one of the major categories contributing to improper E/M payments.
A strong billing workflow therefore starts before the claim reaches the billing department. Providers, coders, and billers need a process that connects documentation to accurate coding and claim submission.
6. Insurance Eligibility and Verification Errors
Eligibility verification helps confirm whether a patient has active coverage and identifies important payer information before or around the time of service.
Failing to verify coverage can create avoidable billing problems.
For example, a patient may have active insurance but a different plan than the one listed in the practice management system. If the claim is sent to the wrong payer, the practice may have to correct and resubmit it.
Eligibility verification should be treated as an ongoing revenue-cycle process, particularly for patients who receive recurring care.
7. Missing Prior Authorization or Referral
Some services require prior authorization, referrals, or other payer-specific requirements.
If the practice does not identify those requirements before providing the service, the resulting claim may be denied.
Authorization requirements vary by payer, plan, service, and patient circumstances. A reliable workflow should therefore include checking the relevant payer requirements before scheduled services when authorization may be necessary.
This is especially important for higher-cost procedures, specialty services, imaging, and treatments that commonly have payer-specific requirements.
8. Duplicate or Incorrect Claim Submission
Submitting the same claim more than once can create unnecessary confusion and additional administrative work.
Duplicate submissions can happen when staff do not have clear visibility into claim status or when a corrected claim is submitted without properly identifying the correction.
Before resubmitting a claim, billing staff should determine whether the original claim was rejected, denied, processed, or is still pending.
A clear claim-status workflow can prevent unnecessary duplicate submissions.
9. Missing or Incomplete Claim Information
Claims require accurate information across multiple fields.
Missing or incorrect provider identifiers, place-of-service information, diagnosis pointers, dates of service, units, patient information, or other required fields can cause a claim to be rejected or require correction.
Claim scrubbing can help identify certain errors before submission, but automated checks should complement not replace human review.
The goal is to submit a clean claim the first time rather than repeatedly correcting preventable problems after submission.
10. Missed Timely Filing and Follow-Up
Even an accurate claim can become a revenue problem if the practice does not monitor it after submission.
Claims can remain unresolved because of payer processing delays, requests for additional information, denials, incorrect payer routing, or other issues.
Timely filing requirements also vary by payer and contract. Waiting too long to correct or resubmit a claim can put reimbursement at risk.
A structured A/R follow-up process should identify aging claims, prioritize high-value balances, track payer responses, and escalate unresolved issues before deadlines become a problem.
Common Medical Billing and Coding Errors at a Glance
| Error | Where It Often Starts | Potential Impact |
|---|---|---|
| Incorrect patient information | Registration | Rejection or delayed processing |
| Incorrect insurance information | Registration / verification | Wrong payer or claim rejection |
| Eligibility not verified | Front desk / verification | Denied claim or wrong payer |
| Incorrect CPT/HCPCS code | Coding | Denial, underpayment, or review |
| Incorrect ICD-10-CM code | Coding | Medical necessity or claim issue |
| Modifier error | Coding / claim review | Denial or incorrect payment |
| Unsupported coding | Documentation / coding | Payment review or denial |
| Missing authorization | Scheduling / verification | Denied service |
| Duplicate claim | Billing / submission | Processing problems |
| Missing claim information | Claim preparation | Rejection or delay |
| Missed follow-up | A/R management | Aging receivables and delayed payment |
How These Errors Affect Practice Revenue
One billing or coding error may appear minor. The financial impact becomes more significant when similar errors happen repeatedly.
Consider a practice that submits hundreds or thousands of claims each month. If a small percentage require correction, staff members must spend time identifying the issue, researching the payer response, correcting the claim, resubmitting it, and monitoring the outcome.
That creates administrative rework.
The financial effects can include:
- Delayed reimbursement
- Higher accounts receivable
- Increased claim denials
- More staff time spent on corrections
- Delayed cash flow
- Additional payer follow-up
- Greater risk of timely filing problems
- Revenue leakage from unresolved balances
The impact also depends on the type of error. A minor demographic correction may be resolved quickly, while a coding or medical necessity issue may require documentation review, provider clarification, or a formal appeal.
This is why practices should look beyond the number of denials and identify the root causes behind them.
Medical Billing Errors vs. Coding Errors
| Medical Billing Errors | Medical Coding Errors |
|---|---|
| Incorrect insurance information | Incorrect CPT code |
| Patient demographic errors | Incorrect ICD-10-CM code |
| Missing authorization | Incorrect modifier |
| Duplicate claim submission | Unsupported code selection |
| Incorrect payer information | Outdated code set usage |
| Missing claim information | Documentation/coding mismatch |
| Timely filing issues | Coding guideline errors |
The two categories often overlap.
For example, a missing diagnosis may appear to be a coding issue, but the underlying problem could begin with incomplete provider documentation. Similarly, an incorrect insurance plan may originate during registration but ultimately cause a billing rejection.
Effective revenue-cycle management looks at the entire workflow instead of treating every denial as an isolated event.
How Practices Can Prevent These Errors
Preventing errors does not require creating a complicated process. It requires consistent checkpoints.
Verify Patient and Insurance Information
Review patient demographics and insurance information at appropriate points in the patient journey.
Confirm:
- Patient name and date of birth
- Member ID
- Group number
- Payer
- Insurance plan
- Coverage status
- Primary and secondary insurance
- Referral or authorization requirements when applicable
Keep Coding Resources Current
Coding guidelines and code sets change over time.
CMS has published FY 2027 ICD-10-CM files effective October 1, 2026, and its HCPCS system also receives quarterly updates.
NCCI edits are also updated quarterly, with the latest practitioner PTP files for the fourth quarter of 2026 effective October 1, 2026.
Practices should make sure coding staff have access to current resources and understand relevant payer-specific requirements. A periodic coding review can help catch outdated code usage before it turns into denials.
Review Documentation Before Claim Submission
Coding should reflect what the provider documented.
If the documentation does not support the selected code, the billing team should have a process for obtaining clarification before the claim is submitted.
Use Claim Scrubbing and Pre-Submission Checks
Automated claim edits can catch certain medical billing and coding errors, like missing or inconsistent information, before submission.
A useful pre-submission review may include:
- Patient information
- Insurance details
- Provider information
- CPT/HCPCS codes
- ICD-10-CM codes
- Modifiers
- Units
- Place of service
- Authorization requirements
- Claim-specific payer rules
Monitor Denials by Root Cause
Do not simply track how many claims were denied.
Track why they were denied.
For example, if a practice repeatedly receives eligibility-related denials, the solution may involve improving front-desk verification. If coding-related denials are increasing, the practice may need a coding review or targeted staff education. A structured denial management process makes these patterns easier to see.
Medical Billing and Coding Error Prevention Checklist
| Before Claim Submission | What to Check |
|---|---|
| Patient information | Name, DOB, demographics |
| Insurance | Member ID, payer, eligibility |
| Documentation | Supports services and diagnoses |
| Coding | CPT, HCPCS, ICD-10-CM |
| Modifiers | Correct and supported |
| Authorization | Required approvals completed |
| Claim details | Provider, POS, dates, units |
| Claim edits | Errors identified and corrected |
What Should a Practice Do When a Claim Is Denied?
A denial should not automatically be treated as a simple resubmission task.
First, identify the payer’s stated reason for the denial. Then determine whether the issue was caused by registration, eligibility, authorization, coding, documentation, claim submission, or another part of the revenue cycle.
A practical denial workflow looks like this:
- Review the denial reason. Understand exactly why the payer did not process or pay the claim as expected.
- Review the original claim. Check the submitted codes, modifiers, patient information, payer information, and other claim details.
- Compare the claim with the medical record. Determine whether the documentation supports the service and coding.
- Correct the underlying problem. Do not simply resubmit the same claim if the original issue remains.
- Resubmit or appeal when appropriate. Follow the payer’s applicable requirements and deadlines.
- Track the outcome. Continue monitoring the claim until it is resolved.
CMS also maintains standardized review and denial-related resources that can help providers understand Medicare claim review and payment issues.
The key is to treat denials as data. Repeated denials often point back to the same medical billing and coding errors showing up at the same step of the workflow.
When Should a Practice Consider Professional Billing Support?
Some practices have enough internal staff and expertise to manage the entire billing cycle themselves. Others find that billing tasks take too much time away from administrative priorities.
Professional medical billing services may be worth considering when a practice experiences:
- Increasing claim denials
- Growing A/R balances
- Frequent coding corrections
- Delayed claim follow-up
- Difficulty keeping up with payer requirements
- Limited internal billing staff
- Inconsistent eligibility verification
- Problems identifying the source of revenue leakage
Outsourcing does not eliminate the need for provider documentation or internal oversight. Instead, the goal is to create a more consistent revenue-cycle process with defined responsibilities, accurate reporting, and timely follow-up.
For practices evaluating outside support, it is important to ask how the billing company handles coding review, claim submission, denial management, A/R follow-up, reporting, payer communication, and compliance.
Related Medical Billing and Coding Topics
Practices researching billing performance may also benefit from reviewing:
- Medical billing services
- Medical coding services
- Denial management
- Revenue cycle management
- Insurance verification
- Prior authorization
- Credentialing and enrollment
- Accounts receivable management
- Payment posting
- Specialty medical billing
These areas are connected. A practice may have accurate coding but still experience payment delays because eligibility verification or authorization processes are inconsistent.
Conclusion
Medical billing and coding errors can affect far more claims than most practices realize. When the same problems repeat, they can cause extra administrative effort, more A/R, delayed reimbursement, and revenue leakage.
Prevention is a lot cheaper than cleanup.
Accurate patient information, up-to-date coding expertise, thorough documentation, proper claim review, verification of eligibility, authorization checks, and regular follow-up on denials can all assist practices establish a more dependable billing procedure.
For practices that continue to experience recurring claim problems, professional billing and revenue-cycle support can provide additional expertise and accountability. Not sure where your claims are getting stuck? You can request a revenue assessment and start with the errors costing you the most.
The goal is not simply to submit more claims. It is to submit accurate claims, identify problems early, and keep reimbursement moving through the revenue cycle.
FAQs
What are the most common medical billing and coding errors?
Mistakes with the patient or insurance information, CPT or ICD-10-CM codes, modifiers, poor documentation, lack of approval, duplicate claims, or missed follow-up are common problems.
Can medical billing and coding errors cause claim denials?
Yes. Claims can be rejected or denied due to coding, documentation, eligibility, authorization, claim information or payer requirements errors.
What is the difference between a billing error and a coding error?
A billing error generally involves claim or patient-account information, while a coding error involves the incorrect selection or reporting of diagnosis, procedure, or service codes. The two can overlap.
How can practices reduce medical billing and coding errors?
Practices can reduce errors by verifying patient information, updating coding resources, reviewing documentation, confirming payer requirements, running pre-submission claim checks, and tracking denials by root cause.
Do coding errors always result in a denial?
No. Some errors may result in incorrect payment, additional review, claim correction, or other processing issues rather than an outright denial.
Why is documentation important for medical coding?
Documentation provides the support needed for the services and diagnoses reported on a claim. If documentation does not support the reported coding, the claim may face payment or review problems.
How often do medical coding rules change?
Payer needs and coding resources may change during the year. Because CMS updates ICD-10-CM annually and HCPCS and NCCI quarterly, clinics need to keep their coding materials current.
What should a practice do after receiving a denied claim?
Review the denial reason and the original claim and supporting medical documents. Identify the problem, fix the issue, and resubmit or appeal according to the payer’s standards and timelines.
Can billing errors increase accounts receivable?
Yes. When claims are rejected, denied, underpaid, or left unresolved, reimbursement can take longer and unpaid balances can remain in A/R.
When should a medical practice consider outsourcing billing?
A practice may consider professional billing support when internal resources struggle with claim follow-up, coding accuracy, denial management, eligibility verification, or growing A/R. The decision should be based on the practice’s workflow, staffing, financial goals, and operational needs.
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