I have done the math for our upcoming September Switzerland trip and the Swiss Pass seems like the best deal for our itinerary. The wildcard is that we plan to travel to Salzburg at the end of our trip. In researching, it sounds like the Swiss Pass should cover our train ride as far as Buchs and that we’d only have to pay for the Buchs -> Salzburg portion of the trip. However, when I attempt to book that trip on SBB, Omio, TrainLine, etc. There doesn’t appear to be an option to indicate the Swiss Pass.

Would I only prebook the Buchs -> Salzburg portion and just show up day of w/ the Swiss Pass for the Zürich -> Buchs portion?

Does anyone have experience travelling out of Switzerland and using the Swiss Pass for a portion? Maybe I’m misunderstanding how it works.

Appreciate any insight!

You don't need to book anything within Switzerland (unless you're taking one of the Panoramic trains). With a valid Swiss Pass, you just hop on the train/bus (unless it's a train, cable car or funicular that is only covered at a discount in which case you'd need to pay before boarding).

You can buy your Buchs to Salzburg ticket here - the Austrian site - https://shop.oebbtickets.at/en/ticket

Not sure why you think there would be an option for the Swiss Pass on a segment not covered by the pass. Perhaps I'm not understanding the question.

Have you looked at the Swiss Pass validity map PDF? Looks to me like the Swiss Pass is good as far as Feldkirch, Austria, which is past Buchs, but I have no idea if that's on the way to Salzburg or not, never visited Salzburg from Switzerland, only Germany.

https://swisstravelpass.com/

Have you looked at the Half Fare Card? It can sometimes be a better deal than the Swiss Pass when it comes to cable cars and funiculars. It doesn't cover museums though.

Yes, I have some experience traveling outside of Switzerland with a Swiss Pass and Half Fare Card - it's usually good to the border station; sometimes slightly beyond.

Our resident Swiss Rail expert neckervd will probably be along soon.