your question was about how much gst on US or international postage. There shouldn't be any. I mail at the post office and if I go in line to buy postage, the clerk doesn't charge me gst if the postage is over 5.00. However, if I buy postage stamps and take them home to put on a package, then I get charged gst. As I understand it, we only pay gst on Cdn postage, unless it is under 5.00. If we buy loose stamps, the clerk can't verify what we're doing with them, so we get charged. linda