The Australian Electoral Commission has a form for those who are unable to vote on the ground of dementia. This form needs to be completed by a member of the family/Enduring Power of Attorney. Once complete the doctor needs to confirm that the patient is unable to vote. You can email the form to us at email@example.com.
Note this form can only be used for those 'who are of unsound mind and incapable of understanding the nature and significance of enrolment and voting.' For those with a disability or mobility restriction please visit the Australian Electoral Commission site for more guidance.