Why Medical Claim Get Rejected: Top 15 Errors and How to Fix Them

The denial letter arrived again. More revenue is delayed, another medical claim is denied, and your employees must put in hours of rework to fix errors that should never have occurred. The figures reveal a sobering tale. According to 41% of healthcare providers, at least 10% of claims are rejected, resulting in billions of dollars in lost or postponed income. Nearly one in five claims (19%) for in-network services were rejected by HealthCare.gov insurers in 2023.
However, the positive reality is that over 33% of avoidable medical claim denials can be successfully appealed, and 90% of all medical claim denials can be avoided.

The difference between successful cash flow and financial hardship is knowing why claims are denied and how to correct these mistakes. The 15 most frequent claim rejection mistakes are broken down in this thorough guide, along with practical fixes for each.

The Rejected Claim Cost

Recognize the true cost of rejections to your practice before getting into specific mistakes. Staff time is needed to look into, fix, and resubmit each rejected claim, which costs between $25 and $117 on average. Many practices lose thousands of dollars every month due to avoidable mistakes as denial rates rise.
Even worse, 33% of avoidable rejections result in lost opportunities where monetary losses are irreversible. That revenue is permanently lost once the timely filing limits have passed.

The Top 15 Mistakes in Medical Claim Rejection

1. Inaccurate or absent patient data

The issue Inaccurate or missing claim data is cited by 50% of providers as the primary cause of rising denial rates in 2025 (a 4% increase from 2024). Immediate rejections result from even small mistakes in patient names, addresses, dates of birth, or insurance information.

Typical Errors

• Patient names that are misspelled
• incorrect birthdate
• Incorrect ID for an insurance member
• Outdated address data
• Absence of demographic information

The Solution

• Check patient data at each visit, not just when a new patient registers.
• Put in place systems for real-time eligibility verification
• Make use of automated data validation tools that identify discrepancies.
• Educate front desk employees on the vital significance of precise data collection
• Patients should be required to digitally confirm information prior to appointments.

2. Problems with Insurance Eligibility and Verification

The Probem

The issue Claims are automatically denied for patients whose coverage has expired, changed, or never existed. Over 25% of respondents claim that incomplete or erroneous information gathered during patient intake accounts for at least 10% of denials.

The Solution

• Real-time insurance eligibility verification during scheduling and check-in
• Verify coverage once more for procedures that are planned weeks in advance.
• Verify the dates of active coverage rather than just the existence of insurance.
• Check for specific service coverage rather than just general eligibility.
• Use timestamps to record every verification action.

3. Prior Authorization Not Obtained

The Problem

Third party providers say prior authorizations are the main reason claims get denied. You can’t get around it—if you give care without the green light, that claim’s going nowhere. Lots of procedures, meds, and tests need pre-approval, and skipping that step always leads to a rejection.

How to fix it

• Keep an up-to-date list of what each payer wants pre-authorized.
• Work those rules right into your scheduling process so nothing slips through.
• Use automated tools to track authorizations, don’t rely on sticky notes or memory.
• Kick off the authorization as soon as you schedule a service.
• Check in on any pending authorizations before the patient shows up.
• Make sure your clinical team knows which services always need prior approval.

4. Coding Errors and Inaccuracies

The Problem

Medical coding isn’t forgiving. One wrong number, and suddenly your claim gets rejected. Mistakes pop up all over, using the wrong CPT codes, mixing up ICD-10 diagnoses, missing updates, unbundling when you shouldn’t, or just tacking on the wrong modifier.

How to fix it

• Hire certified pros. CPCs, CCSs, people who know their stuff.
• Bring in coding software that double-checks and flags mistakes before they cause trouble.
• Do regular coding audits. Seriously, don’t skip them.
• Stay on top of updates. Subscribe to services that alert you right away when something changes.
• Build coding guides just for your specialty. Set up coder peer reviews so fresh eyes can catch what you missed.

5. Lack of Medical Necessity Documentation

The Problem

Insurance companies often reject claims because they don’t see clear proof that a treatment was actually needed. If there’s no solid explanation in the records, they usually just say no.

How to fix it

• Make sure providers write down exactly why each service was necessary in their notes.
• Connect diagnosis codes directly to the procedures to show the medical reason behind them.
• Add extra paperwork when something is unusual or expensive.
• Teach providers what insurers look for, especially with common reasons claims get denied.
• Use clinical decision support tools to point out what documentation is needed.

6. Duplicate Claims Submission

The Problem

Submitting a claim more than once (maybe by accident or just trying to check its status) usually gets it flagged and rejected as a duplicate. It slows everything down and holds up real reimbursements.

The Fix

• Set up tracking systems so the same claim can’t get submitted twice.
• Make sure staff always check the status before they try again.
• Work with clearinghouses that spot duplicates right away.
• Lay out clear rules for when it’s okay to resubmit.
• Keep a record of every submission, with dates and confirmation numbers.

Also Read: Burnout in Medical Billing: Why It Happens and How to..

8. Incorrect or Missing Modifiers

The Problem

Modifiers tell the full story about how a service was performed. Leave one out or use the wrong one, and you end up with claims that get bundled the wrong way, underpaid, or just flat-out denied.

How to fix it

• Keep quick-reference guides handy for the modifiers you use all the time.
• Use automated tools that suggest the right modifiers as you code.
• Make sure coders really know when and how to use modifiers.
• Double-check claims for modifier accuracy before sending them off.
• Build modifier protocols tailored to each specialty.

9. Non-Covered Services

The Problem:

If you submit claims for stuff the patient’s plan doesn’t cover (i.e. included procedures, anything over their benefit limit, or care from out-of-network providers) it’s going to get denied. No surprise there.

How to handle this:

• Check if the procedure’s actually covered when you verify eligibility.
• Get all the benefit details up front, know the exclusions and any limits.
• Tell patients ahead of time about what their plan won’t pay for.
• Ask for payment up front if the service isn’t covered.
• Make sure you have proof the patient understands and agrees to this.

10. Coordination of Benefits Errors

The Problem

When patients have multiple insurance policies, claims must be filed with the correct primary and secondary insurers in proper sequence. Filing in wrong order or with incorrect information causes denials.

The Fix

• Ask about secondary insurance at every visit
• Verify primary vs. secondary payer status
• File claims in correct sequence
• Include other insurance information on claims
• Use coordination of benefits tools automating proper filing order

11. Billing the Wrong Payer

The Problem

When you send a claim to the wrong insurance company, it’s not going anywhere. Usually, this happens because someone’s using old info or the patient gave details that aren’t quite right. The claim bounces back, and now you’re stuck waiting even longer for payment.

How to fix it

• Check the patient’s insurance every time they come in, not just the first visit.
• Ask if their insurance card has changed since you last saw them.
• Run electronic checks to make sure you’ve got the right payer.
• Update your records right away if there’s a change.
• And don’t just take the patient’s word for it, always double-check those details.

12. Missing or Invalid Provider Information

The Problem

When you file claims, you need the right details for the rendering provider, the referring provider, and the facility, stuff like NPIs and tax IDs. If any of that info is missing or wrong, your claim gets kicked back.

How do you fix it

• Keep your provider credentialing database up to date.
• Double-check those NPI numbers, they need to be current and linked to the right people.
• Make sure the facility’s NPI matches the actual place the service happened.
• Don’t forget to add the referring provider’s info when it’s needed.
• And, just to stay on top of things, audit your provider details regularly so everything stays accurate.

13. Unbundling and Upcoding Issues

The Problem

When people bill separately for services that should be bundled together, or code things as more complex than they really are, it sets off compliance alarms and leads to denied claims. More than half (54% say) are seeing more errors in claims lately.

How to fix it

• Know the National Correct Coding Initiative (NCCI) edits inside out.
• Use claim scrubbing software to catch bundling mistakes before they slip through.
• Only code for the services you actually provided and have the paperwork to back it up.
• Make sure coders really get the rules for picking the right codes.
• Run regular compliance audits to catch problems early.

14. Incomplete or Illegible Documentation

The Problem

Missing, incomplete, or hard-to-read documentation makes it tough for payers to confirm that services happened as billed. They end up denying claims or asking for more details, which just slows everything down.

The Fix

• Switch to electronic health records to wipe out legibility problems.
• Set clear deadlines for finishing documentation.
• Use clinical templates so nothing important gets left out.
• Train providers on what “complete documentation” actually means.
• Check documentation quality on a regular basis.

15. Service Date Errors

The Problem

When service dates are wrong (maybe it’s an admission date, a discharge date, or just the range of days) claims get kicked back or processed all wrong.

The Fix

• Double-check dates as you enter charges
• Compare dates with the appointment schedule
• Set up validation rules that catch date mistakes
• Teach billing staff how to enter dates correctly for each claim type
• Look over date fields while scrubbing claims

Prevention Strategies (Avoiding Medical Claims) That Actually Make a Difference

Don’t just fix mistakes one by one. Instead, set up real systems to stop them in the first place. Here’s how:

• Automated claim scrubbing works wonders: The right software checks each claim against thousands of rules before you even send it off. It catches more than 95% of errors right away.
• Keep your team in the loop: Run regular training sessions so everyone stays current on coding changes, payer rules, and the usual slip-ups.
• Make audits part of your routine: Do a monthly internal review to spot patterns and catch bigger problems before they turn expensive.
• Invest in the right technology: Good revenue cycle management systems, especially those with AI-driven coding and validation, drive error rates way down.
• Clear Communication: Set up clear ways for coders to ask providers about any questionable documentation as soon as it comes up.

When It’s Time to Call in the Professionals

Keeping billing flawless isn’t easy. Most practices just don’t have the tools, staff, or know-how to catch every mistake. In fact, almost 70% of providers say it’s tougher to submit clean claims now than it was just a year ago. If your team keeps running into denied claims, doesn’t have certified coders, deals with constant staffing headaches, or can’t swing the latest tech, it’s probably smarter (and cheaper) to bring in professional medical billing experts.

Also Read: From Rejection to Reimbursements: The 72 Hours Rule That’s Transforming

Why choose RBS Innovators LLC?

We’re all about stopping claim rejections before they start. Seriously, that’s our mission. We mix certified coding know-how, smart AI for claim scrubbing, real-time eligibility checks, and automated denial management. The result? Our clients see clean claim rates above 95%, month after month.

Here’s what we deliver:

• 95%+ clean claim rates
• Denials under 5%
• Days in A/R cut by 30–40%
• Zero missed filing deadlines
• Monthly reports that lay out every metric you care about

What makes us different?

• Deep expertise in specialty-specific coding
• Tech that catches mistakes before your claims ever go out
• We spot and fix problems early, thanks to proactive communication
• Our pricing is clear. No hidden fees, no surprises
• We guarantee our results, so you know exactly what you’re getting

Take Action Today!

Don’t let rejected claims hold back money you’ve already earned. Every medical claim denial means more time wasted fixing mistakes instead of moving forward. And you’re not alone, over half of providers say claims errors are only getting worse.

Let RBS Innovators LLC take a look at your recent denials. We’ll dig into the details, show you exactly where things are going wrong, and break down what these mistakes are costing you every month. You’ll get a clear, customized plan to help you fix the problem. No strings attached. No sales pitch. Just straight answers.