I've noticed over several federal elections in Australia that around 70% of the votes are counted on election night. However, it then takes days, sometimes weeks to count the remaining 30% of the votes. What are the reasons for this? Does the percentage vote count reflect the true number of votes counted up to that point? Are fewer AEC staff employed to count the remaining votes? Is the count complicated by preferences?
The remaining votes are declaration votes, which include absent votes and provisional votes, as well as postal votes. Declaration votes and postal votes are ballot papers enclosed in an envelope with the voter's details written on it, allowing AEC officials to make a decision on the voter's eligibility to vote before admitting or rejecting the ballot papers inside.
This process (preliminary scrutiny) only occurs after polling day, and it can take up to 13 days for postal votes and other declaration votes to reach the office of the relevant electoral division.