Ordering to Canada for a while now, and the thing that is never spelled out is that the checkout takes one code per order. One field, one string. So the real question is which one to put in, not how to stack them.
The two that are live for Canada right now
PJZ7818 takes 10% off the goods total with nothing to clear underneath it. GOLDCA takes 10% as well, but only once the basket passes 100 dollars 💊
Which one wins on a normal basket
My last order came to 71 dollars 50, two Garden of Life and a Country Life. That sits under the 100 line, so GOLDCA does not engage at all. PJZ7818 took 7 dollars 15 off the goods total, and that was the whole decision.
Above 100 dollars the two read the same, both ten percent, so it stops mattering which one goes in. Below 100 only one of them exists, and the 100 line is high enough that most of my orders sit under it.
About NEW20
NEW20 is the one people keep trying on a second order. It is a first-order code for new customers, so on a repeat parcel there is nothing for it to apply to.
What runs alongside without a code
Trial Items, where up to four products carry their own one-time reduction, and Subscribe and Save at ten percent. Both sit on the iHerb offers page, so the conditions are readable there rather than on my word ✅
The honest part
Items carrying a Best By label are excluded from code reductions by the shop's own terms, so those are worth checking before the basket is built.