Recommendation 18 (Internet Voting) Estonia 2011
http://aceproject.org/ero-en/regions/europe/EE/estonia-elections-assessment-mission-report/at_download/file
Given the trend of ever greater use of Internet voting, with a significant proportion of the electorate voting before the end of the campaign period, consideration could be given to enabling voters who voted remotely via the Internet to change their vote with a paper ballot on election day.