Many thanks to SWLing Post contributor Paul Evans for pointing us to this update from the Universal Postal Union (UPU): after nearly 120 years since their introduction in 1907, International Reply Coupons (IRCs) are being phased out as of 31 December 2026.
IRCs have long served as a universal postage currency, allowing SWLs to prepay return postage for international listener reports in the postal systems of the UPU’s 192 member countries. The UPU’s decision to discontinue IRCs reflects broader changes in international postal services and the shift toward digital communication, but existing coupons will remain valid and exchangeable through the end of 2026. A special commemorative product marking the IRC’s legacy is also planned as part of this transition.
Read the full press release here: https://www.upu.int/en/press-release/2025/end-of-a-chapter-start-of-a-legacy-the-international-reply-coupon-enters-the-history-books

I remember using these as a young ham in the 70’s. Thanks for the post Paul and Thomas for posting.
I had some delivered from Switzerland so I could QSL with the United Nations station 4U1UN: https://4u1un.net/4u1un-qsl-policy.html
So I have 9 more I need to use! What other cool stations use IRCs?