Top 5 Reasons WSIB Claims Get Denied (And How to Fight Back)
Every year, thousands of Ontario workers file claims with the Workplace Safety and Insurance Board (WSIB), expecting the system to support them after a workplace injury. But too many of those claims come back denied. According to WSIB data, roughly 17,500 to 18,750 claims are denied annually in the province, leaving injured workers scrambling to pay bills, cover medical costs, and keep their families afloat.
Connect with a verified WSIB lawyer or paralegal on ClaimIt to get help with a denied claim today.
If your WSIB claim was denied, you are not alone. Understanding why claims get denied is the first step toward fighting back and getting the benefits you deserve. Below, we break down the five most common reasons WSIB denials happen, what you can do about each one, and when it makes sense to bring in professional help.
1. Insufficient Medical Evidence
The most frequent reason WSIB claims get denied is a lack of adequate medical documentation. WSIB requires clear, detailed medical evidence linking your injury or illness directly to your workplace. If your medical records are vague, incomplete, or fail to establish that connection, your claim is at risk.
Common problems include:
- Doctor's notes that describe symptoms but do not specify how the injury happened at work
- Gaps between the date of injury and the first medical visit
- Missing diagnostic tests, imaging results, or specialist referrals that support the diagnosis
- Incomplete functional abilities forms (FAFs) that do not capture the full extent of your limitations
How to Fight Back
Request copies of all your medical records and review them before submitting your claim. Make sure your doctor clearly states the connection between your injury and your job duties. If your initial documentation was weak, ask your doctor to write a supplementary report that spells out the workplace link. For chronic pain or psychological injury claims, consider getting an assessment from a specialist who understands WSIB requirements.
A WSIB paralegal can review your medical evidence and identify gaps before they become grounds for denial.
2. Late Reporting or Missed Deadlines
Timing matters more than most workers realize. WSIB expects injuries to be reported promptly, both to your employer and to the board. When there is a significant delay between the injury and the report, WSIB may question whether the injury is legitimate or whether it actually happened at work.
Key deadlines to be aware of:
- Report to your employer as soon as possible after the injury occurs
- Your employer must file a Form 7 within three business days of learning about the injury
- You should file a Worker's Report (Form 6) directly with WSIB, especially if you believe your employer may delay
- Appeals must be filed within six months of the decision date for most WSIB decisions, or within 30 days for some specific decision types
How to Fight Back
If you missed a reporting deadline, do not assume your claim is dead. File your report as soon as possible and include an explanation for the delay. Valid reasons can include not realizing the severity of the injury at first, being hospitalized, or not understanding the reporting process. WSIB does consider late reports on a case-by-case basis.
If your employer failed to file the Form 7, document this in writing. You have the right to file your own claim directly with WSIB. Learn more about the appeal timeline in our guide to the WSIB appeal process in Ontario.
What Happens When Your WSIB Claim Gets Denied?
When WSIB denies your claim, you receive a written decision letter explaining the reason. This letter is not the end of the road. You have the right to appeal, and many denied claims are overturned on appeal when stronger evidence is presented. The appeal process starts with a request for reconsideration by WSIB, and if that fails, you can escalate to the Workplace Safety and Insurance Appeals Tribunal (WSIAT).
For a full breakdown of what to do immediately after a denial, read our article on what to do when your WSIB claim is denied.
Browse verified WSIB representatives on ClaimIt who have handled thousands of denied claims across Ontario.
3. Pre-Existing Conditions
WSIB may deny a claim if they determine your injury or illness was caused by a pre-existing condition rather than your workplace. This is one of the most frustrating reasons for denial because many workers have underlying conditions that a workplace incident aggravated or worsened.
The reality is that you do not need to be in perfect health to qualify for WSIB benefits. Under Ontario law, if your job duties aggravated, accelerated, or worsened a pre-existing condition, you may still be entitled to compensation. WSIB calls this the "thin skull" principle: employers must take workers as they find them.
How to Fight Back
If your claim was denied because of a pre-existing condition, gather medical evidence showing how your job duties worsened your condition. A timeline comparing your health before and after the workplace incident can be powerful evidence. Ask your doctor to provide a detailed letter distinguishing between your baseline condition and the workplace aggravation.
Workers with chronic pain, degenerative disc disease, or mental health conditions are especially vulnerable to this type of denial. A legal representative experienced in WSIB cases can help you build the medical case that proves the work-related aggravation.
4. Employer Disputes and Contradictory Statements
Your employer has the right to submit their own account of what happened, and their version does not always match yours. WSIB considers employer statements when deciding claims, and a strong objection from your employer can tip the scale against you.
Common employer dispute scenarios include:
- Your employer claims the injury did not happen at work or during work hours
- Supervisors provide statements contradicting your account of the incident
- Your employer argues the injury resulted from horseplay or a violation of safety rules
- Surveillance footage or timekeeping records that seem to conflict with your report
How to Fight Back
Document everything from the moment the injury happens. Take photographs of the scene if possible. Get contact information for any coworkers who witnessed the incident and ask them to provide written statements. Save any text messages, emails, or incident reports related to the injury.
If your employer is actively disputing your claim, having professional representation becomes even more important. WSIB representatives who have handled WSIB appeals know how to counter employer objections with evidence and legal arguments. Some of the representatives on ClaimIt are former WSIB insiders who understand how the board weighs employer statements.
How Much Does It Cost to Fight a WSIB Denial?
Cost is one of the biggest concerns for injured workers considering professional help. The good news: most WSIB lawyers and paralegals work on a contingency fee basis, which means you pay nothing upfront. The representative only gets paid if you win your case, typically around 30% of the benefits recovered.
ClaimIt is completely free for injured workers to use. You can browse representative profiles, compare experience levels and success rates, and submit an intake form at no cost. For a detailed breakdown of legal costs, read our guide on WSIB lawyer costs in Ontario.
5. The Injury Is Not Considered Work-Related
WSIB only covers injuries and illnesses that arise "out of and in the course of employment." If the board determines your condition is not connected to your job, the claim will be denied. This can happen with repetitive strain injuries, occupational diseases, and mental health conditions where the work connection is less obvious than a single acute incident.
Examples of claims that commonly face this challenge:
- Carpal tunnel syndrome or other repetitive strain injuries
- Chronic back pain that developed gradually over months or years
- Work-related stress, anxiety, or PTSD (covered under traumatic mental stress provisions)
- Occupational diseases with long latency periods, like cancers linked to workplace chemical exposure
How to Fight Back
For repetitive strain and gradual onset injuries, a detailed job description outlining the physical demands of your role is critical. Ask your employer for a physical demands analysis (PDA) if one exists. Your doctor should clearly link the diagnosis to specific workplace activities, not just note that you have the condition.
For occupational diseases, Ontario has a list of presumptive conditions for certain occupations (particularly firefighters and first responders). If your condition is on that list, the burden of proof shifts in your favor. For conditions not on the list, an occupational health specialist's opinion can strengthen your case.
Submit a free intake form on ClaimIt to get connected with a WSIB specialist who handles cases like yours.
Do You Need a Lawyer or Paralegal for a WSIB Denial?
You can file a WSIB appeal on your own, but the process is complex and the stakes are high. Workers who have professional representation tend to have better outcomes, especially when the denial involves medical evidence disputes, employer objections, or pre-existing condition arguments.
Here is when professional help makes the biggest difference:
- Your claim was denied due to insufficient medical evidence and you need help gathering the right documentation
- Your employer is actively disputing the claim
- You are appealing to WSIAT and need someone who understands tribunal procedures
- The denial involves a complex issue like a pre-existing condition, occupational disease, or mental health claim
For free initial guidance, check out our article on getting a free WSIB consultation.
Frequently Asked Questions
What is the most common reason WSIB denies claims?
Insufficient medical evidence is the most common reason WSIB claims get denied. Claims that lack detailed medical documentation linking the injury to the workplace are far more likely to be turned down. Always ensure your doctor clearly explains how your work duties caused or contributed to your condition.
Can I appeal a WSIB denial on my own?
Yes, you can appeal a WSIB denial without a lawyer or paralegal. However, the appeal process involves strict deadlines, evidence requirements, and hearings that can be difficult to handle alone. Workers with professional representation often have stronger outcomes, especially in complex cases.
How long do I have to appeal a WSIB decision in Ontario?
For most WSIB decisions, you have six months from the date of the decision to file an appeal. Some specific decision types have a 30-day deadline. Missing the deadline can make it much harder to get your case reconsidered, so act quickly once you receive a denial letter.
Does WSIB deny claims for pre-existing conditions?
WSIB may deny claims if they believe a pre-existing condition, not workplace activity, caused the injury. However, Ontario's "thin skull" rule means employers must take workers as they find them. If your job aggravated or worsened a pre-existing condition, you may still qualify for benefits. Medical evidence showing the workplace impact is the key to winning these cases.
Is ClaimIt free for injured workers?
Yes, ClaimIt is completely free for injured workers to use. You can browse representative profiles, compare experience and success rates, and submit intake forms at no cost. Most representatives on the platform work on contingency, meaning you only pay if you win your case.
Take Action Before Time Runs Out
A denied WSIB claim does not have to be the final word. Thousands of Ontario workers successfully overturn denials every year by gathering better evidence, meeting deadlines, and getting the right help. The longer you wait, the harder it becomes to gather evidence and meet appeal deadlines.
Start by reviewing the specific reason for your denial. Then take steps to address the issue, whether that means strengthening your medical documentation, correcting the record about how your injury happened, or building a case that your job worsened a pre-existing condition.
If you need professional help, ClaimIt connects you with verified WSIB lawyers and paralegals across Ontario who offer free consultations and work on contingency. You can compare representatives by experience, cases handled, and areas of specialty, all in one place.
Find a WSIB representative on ClaimIt now and start fighting back.
Need Help With Your WSIB Claim?
Connect with a verified WSIB lawyer or paralegal in Ontario. Most offer free consultations and work on contingency.
Find a Representative