Buy your shop cards from Costco Canada.

If you carry the Atmos Summit card and you're buying shop cards, buy them from costco.ca instead of the US site. The charge runs through a Canadian merchant, so it codes as a foreign transaction and earns the card's 3x. Same cards, better rate.

A few things to know first:

• costco.ca sells bigger denominations than the US site, so you can move more per order.
• The cards are priced in Canadian dollars, so what you pay moves with the exchange rate.
• You have two ways to use them. To lock in today's rate, spend the Canadian cards on USD shop cards right away. If you'd rather not bother, just use them like any other shop card and it converts on the fly.
• You'll need a separate costco.ca account, but you can sign in with your existing membership info.

It's a bit of setup, then every shop-card run after that earns triple. And as always with category coding, it can shift, so watch how the first charge posts before you go big.