18. Is there a limit on the amount a donor can contribute to a candidate?

Source

The only requirement is that donations recieved by candidates above the threshold limit are reported in the candiate's electoral return to the Australian Electoral Commission.Commission.

Sources: Australian Election Commission Transparency Register  see https://www.aec.gov.au/Parties_and_Representatives/financial_disclosure/transparency-register/ . Australian Electoral Commission Disclosure Threshold, see https://www.aec.gov.au/Parties_and_Representatives/public_funding/threshold.htm