Many workplace accidents can lead to injury: a fall from ladder, catching your sleeve in machinery or tripping over a box on the floor. Some accidents are more serious than others. You may wind up in the hospital, missing time from work and have mounting medical bills.

When you get injured at work, you can file a workers’ compensation claim to cover medical costs and missed pay. However, an employer may deny your claim. Here are four reasons an employer may try to deny a claim and how you can fight back.

You did not report the injury in time

In Pennsylvania, you must report a work injury within 120 days after it occurs. Failing to do so could cause your workers’ compensation claim to be denied. However, the longer you wait, the more it weakens your case. It is much wiser to report a work injury right after it happens.

You did not file a workers’ compensation claim in time

More than just reporting the accident, you also must file workers’ compensation paperwork. You have three years after the injury occurs to file, so meeting that deadline is generally not an issue. Again, the sooner you file, the more likely you will be believed.

Employer denies the injury occurred at work

An employer may allege your injury did not occur at work. You can counter this claim by getting a coworker to verify the accident. The doctor that examines may also be able to provide proof that your injury happened at work. But again, the sooner you report it, the more believable your story.

The injury is not covered

Some workplace injuries are more difficult to prove. If you suffer a suffer stress-related injury or some other sort of psychological illness, your employer may claim it is not covered. Proving a psychological illness is harder. However, work conditions can cause serious mental illnesses, and workers’ compensation should cover these. You may want to contact an attorney experienced in workers’ compensation matters to help you build your case.

If you suffer from a condition like mesothelioma, you will need evidence to prove your work environment caused it. With these illnesses, the workers’ compensation deadline is extended, since the symptoms may not manifest for years. Again, these cases are more complex.

You can appeal a workers’ compensation claim denial. To prove your case, you need evidence that contradicts your employer’s claims. This will likely include your medical records, accounts from your coworkers and your testimony regarding the accident. You may also need evidence from your workplace, particularly if your injury involved exposure to a toxic substance. Do not let a denial or benefits stop you from getting the compensation you need to heal.