"Just follow the instructions and tick the box next to the flag you want to be the New Zealand flag," said Mr Peden.
Replacement voting papers are available at www.elections.org.nz/. For more information about replacement papers, call 0800 36 76 56 (from within New Zealand) or +64 9 909 4182 (from overseas).
"Replacement papers can only be issued until Monday 21 March, so if you haven't received your paper, contact us right away," said Mr Peden.
"We want to make sure no enrolled voters miss out on the chance to have their say."
Only people who were correctly enrolled by March 2, 2016 are eligible to vote in the referendum.
Voting closes on March 24, and the Commission encourages voters to post their voting papers back by Monday, March 21 to make sure they arrive in time.
More information about voting in the referendum is available at 0800 36 76 56 and at www.elections.org.nz/flag.