Australia unfair dismissal: how long must I have worked for the employer?

For ordinary unfair dismissal protection under the national system, the usual minimum employment period is 6 months, or 12 months if the employer is a small business with fewer than 15 employees. Other eligibility rules also apply, and some dismissal claims use different legal routes. Official source: Fair Work Ombudsman. Guide: https://getinstantlaw.com/employment-workplace-problems/fired-from-job