Graham, VK6RO has dropped us a line to let you know that the "Nairobi" type of International Reply Coupon or IRC, EXPIRES ON DECEMBER 31 2013 and will no longer be exchanged by Australia Post after that date.
The new "Doha" version has been available since July 1 2013 and expires 31 December 2017. The names relate the city in which the International postal union held meetings.
Check the expiry date on your IRCs now. Graham recently exchanged all his "old" IRCs and each one was exchanged for $2.60 value.
Some Post Offices will have no idea what you’re talking about, so be prepared with this:
The International Post services guide – May 2013 • Section 2 – International Post services:
In Australia, a holder of an International Reply Coupon may redeem it at any Australia Post retail outlet. They receive a stamp or stamps to the value of the postage for an Air Mail Letter up to 50 grams at the Rest of the World rate – refer to the Post Charges Booklet (8833665)