From 1 July 2014, if a skills assessment is mandatory as part of a visa application, that assessment will only be valid for a period of three years from the date of issue, unless a shorter validity period is specified on the assessment.
DIBP. (2014, July 03). SkillSelect. Retrieved from Department of Immigration and Border Protection: http://www.immi.gov.au/Work/Pages/SkillSelect/SkillSelect.aspx#tab-content-2