“They Say It Was Already There!” | WSIB Blamed a Pre-Existing Condition? What the Rules Actually Say

Many people have an old back problem, a worn knee or a past injury. If the WSIB points to yours, it can feel like your claim is over. It is not. The rules are more protective than most people expect.

Can the WSIB deny my claim because of an old condition?

No. The WSIB's policy on pre-existing conditions says entitlement for a work-related injury or disease "will not be denied due to the existence of a pre-existing condition." The policy applies to all decisions made on or after 1 November 2014.

So where does an old condition matter?

Later, when the WSIB looks at your ongoing impairment. The question becomes whether the work injury is still a significant contributing factor to how you are now.

The policy compares the work injury with the old condition. If the work injury alone would have caused a similar level of impairment, it still counts as significant.

What does aggravation mean?

An aggravation is when a work injury makes an existing condition worse. The policy says benefits for an aggravation continue until you recover from the aggravation, meaning until you are back to how you were before the work injury.

That is why the most important evidence is about how you were before.

What evidence helps?

• Your life before the injury. Full duties at work, no time off, no restrictions, the sports or tasks you did without trouble.
• Your medical history. Gaps in treatment for the old condition, or records showing it was stable.
• The change. Your first medical notes after the work injury, and how they differ from earlier ones.
• A clear opinion. A doctor or specialist who addresses whether the work injury is a significant contributing factor, using those words.
• Your own record. A dated log of symptoms and what you can and cannot do, from the start.

What if a decision says my problems are now from the old condition?

You can object, usually within six months, under section 120 of the Workplace Safety and Insurance Act. The deadline printed on your decision letter is the one that applies. New medical information that speaks to the significant contributing factor test is what most often changes these decisions. Our article “WSIB Rejected My Claim!” | WSIB Denied Your Claim? Your Next Steps Before the Deadline explains the first steps.

Who can help?

The Office of the Worker Adviser, if you are not in a union. It is an independent agency of the Ontario government, and its service to non-unionized injured workers is free. Its number for English service is 1-800-435-8980. If you are in a union, start with your union representative. A community legal clinic is another free route.

Read next

• “I Think WSIB Got It Wrong!” | Disagree With a WSIB Decision? How to Appeal, Step by Step
• “That Number Seems Wrong!” | Is Your WSIB NEL Award Too Low? How It Is Worked Out and What to Check
• “It Hurts More After Every Shift!” | Hurt Over Time, Not in One Moment? How WSIB Handles Repetitive Strain

If your recovery were reviewed tomorrow, what would your record say?

The National Workplace Injury Recovery Guide is where your recovery gets documented, day by day. Symptoms, appointments, calls and costs, written while they are fresh. It works in every province and it stands on its own.

See the National Guide$39

Both guides, $39 until 22 November. Add the Ontario Workplace Injury Companion Guide for the dates and rules that shape your recovery in Ontario, and the discount applies at checkout. Bought separately: $63.99.

Every figure in this article comes from a named source. How we check
Last verified: October 2026.