What if I held onto the reply-paid envelope for, say, six months, and sent it back to them then? There must be a term limit on the parties claiming postage back from the taxpayer, but that reply-paid envelope will probably work for years.
@futzle I suspect it depends if the AusPost billing account is held by the political party or by the individual politician (who may or may not get reelected). The one I got the mail is going back to a specific politician's local office