Under the Fair Work Act you are treated as having been dismissed if you resigned but were forced to do so because of conduct, or a course of conduct, engaged in by your employer.
Two paths get you there.
1. The employer intended to force the resignation
The employer engaged in conduct with the intention of bringing the employment to an end. "Resign or we terminate you" is the clearest example. So is being handed a resignation letter to sign.
2. Resignation was the probable result of the employer's conduct
The employer's conduct left you no real choice but to resign. The employer's intention is not the question. The question is whether a reasonable person in your position would have felt they had no effective alternative.
Examples that have been argued successfully include a substantial and unilateral reduction in pay or hours, a demotion without contractual authority, sustained bullying that the employer knew about and failed to address, and a fundamental change to the role that amounts to a repudiation of the contract.
What does not work
- Resigning because you were unhappy, stressed, or did not like your manager.
- Resigning in the heat of an argument and regretting it the next day. (Though a resignation given in the heat of the moment may not be effective at all, which is a different argument.)
- Resigning because you were performance-managed, unless the process itself was a sham or a device.
- Resigning to avoid a disciplinary process where the process was fair.
The bar is genuinely high. Employers know it. If you are considering resigning right now because your situation has become intolerable, speak to someone before you do, not after. Once you resign, your position is materially weaker.
The clock still runs
If a constructive dismissal is made out, the dismissal took effect on the date your resignation took effect. The 21 day deadline runs from then.
Constructive dismissal or general protections?
Conduct that forces a resignation is sometimes also adverse action. If you were pushed out after making a complaint, taking sick leave, or asserting an entitlement, you may have a general protections claim instead, and it may be the stronger one.
Read: Unfair dismissal vs general protections
Call 1800 UNFAIR before you resign, if you still can.