It may be unlawful if your employer dismisses you for the reason that you were absent from work due to illness or injury, even if the absence is for an extended period.
Section 352 of the Fair Work Act 2009 (Cth) states that an employer must not dismiss an employee because the employee is temporarily absent from work because of illness or injury “of a kind prescribed by the regulations”. This protection is valid for any period of absence for up to three months. If you are dismissed due to taking leave for illness and/or injury, and you have not been absent from work for a period of three months, please contact an employment lawyer.
If you have been absent from work for over three months or an accumulated period of over three months in a twelve-month period and you were not on paid personal or carer’s leave during that time, the protection under section 352 will have ceased as per 3.01 of the Fair Work Regulations 2009. Regulation 3.01 also outlines further requirements for medical certificate submissions and evidence requirements for a period of paid personal leave.
The above exception to the general rule found in section 352 of the Fair Work Act 2009 (Cth) was applied in Nikolich v Goldman Sachs J B Were Services Pty Ltd  FCA 784 (23 June 2006), where the Applicant was absent from work due to a mental illness caused by workplace bullying. The Federal Court found that despite there being adequate medical certificates to cover the dates in question, the Applicant’s absence from work had been more than a three-month continuous and accumulated period.
In addition to the above, if you have been covered under any statutory compensation or insurance such as WorkCover, the period of absence taken under WorkCover will not be counted in calculating the three-month leave period.
If your employment has been terminated due to a long absence caused by illness or injury, it is important to note that employers must still follow the appropriate procedures for carrying out a dismissal. You may be entitled to challenge the termination of your employment on grounds other than a potential breach of section 352 of the Fair Work Act 2009 (Cth). This includes an unfair dismissal application if the reason for dismissal was harsh, unjust or unreasonable or if a valid process was not followed; a general protections claim if the reason for dismissal was for a prohibited reason; alternatively a claim under state or federal anti-discrimination law where applicable.