Can My Employer End My Job Because of a Long Illness?

When someone is off sick for a long time, employers sometimes send a letter saying the employment contract has been "frustrated" and that nothing is owed. It sounds official and final. In reality, frustration is a narrow doctrine with a high bar, and even when it genuinely applies to an illness, Ontario law still guarantees you a floor of pay. It is rarely the clean exit employers present it as.

What is frustration of contract?

Frustration is a legal doctrine that ends a contract when an unforeseen event, through no fault of either party, makes performance impossible or radically different from what was agreed. In the employment context, the classic example is an illness or injury that leaves an employee permanently or indefinitely unable to do the job. The Court of Appeal applied the doctrine in Croke v. VuPoint System Ltd. (2024 ONCA 354), confirming that a genuine supervening event outside the parties' control can frustrate an employment contract. The key is that the event must truly make continued performance impossible, not merely inconvenient.

The bar is high: no reasonable prospect of return

A long absence, on its own, is not frustration. An employer has to show, on the evidence, that there is no reasonable prospect you will be able to return to work in the foreseeable future. That is a demanding, forward-looking test that depends on medical evidence, not on the employer's impatience. If your prognosis is uncertain, or your doctors expect you to recover in time, a frustration claim is usually premature.

Your employer has to accommodate first

Before an employer can rely on frustration, it must have met its duty to accommodate your disability to the point of undue hardship. An employer that never explored modified duties, a graduated return, or suitable alternative work cannot simply declare the contract frustrated. This tension between accommodation and frustration was central in Ontario (Human Rights Commission) v. Dofasco Inc. (2001 CanLII 2554), where the availability of suitable alternative work was directly relevant to whether the relationship had actually ended. Skipping accommodation and jumping to frustration is a common and costly employer mistake.

You still keep your ESA minimums

This is the part most employers do not mention. Ontario's ESA rules (Regulation 288/01) generally exempt an employer from paying termination and severance pay when a contract is frustrated by an unforeseeable event, but that exemption expressly does not apply where the frustration results from the employee's illness or injury. In plain terms: if a long illness frustrates your contract, your employer still owes you your ESA termination pay and, if you qualify, statutory severance pay. So even a valid frustration claim is not a way for the employer to pay nothing.

What if frustration is claimed too early?

Then it is not frustration at all, it is a dismissal. Employers sometimes use "frustration" as a label to end a sick employee's job while paying less than a proper severance. In Forsyth v. Blue Rock Wealth Management Inc. (2015 ONSC 6666), the employer argued the contract was frustrated by the employee's inability to return from disability leave, the kind of claim that has to be tested against the evidence rather than accepted at face value. If the frustration does not hold up, the ending of your employment is a wrongful dismissal, and you are owed common law reasonable notice, often far more than the ESA minimum.

What should you do if your employer claims frustration?

1. 1.Do not accept a frustration letter as the final word, and do not sign a release based on it.
2. 2.Keep your medical evidence, especially anything about your prognosis and expected return.
3. 3.Note whether the employer ever offered accommodation or suitable alternative work.
4. 4.Get advice. A free review can tell you whether the frustration claim holds up and what you are owed.

Frustration sits right next to a dismissal during a medical leave and the duty to accommodate. If the claim fails, your entitlement is your full severance, and if your illness was really being used against you, you may also have a human rights claim.

About the Author

Carmen Reyes

Legal Writer, Mirza Law

Carmen Reyes is a legal writer at Mirza Law in Toronto. She writes about constructive dismissal, workplace changes, and how Ontario employees can protect themselves when their job changes under them.

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