I'm a US Permanent resident green card holder, planning to visit Canada in December. I'm in the middle of renewing my green card (Expiration date 12/17/17 but get extension until Aug 2018 when I applied for renewal). If I apply eTA with my current green card, do I have to re-apply another eTA if i receive my new green card before my travel date?
As written by @phoog:
It's a good question, but if I were you I would just plan to apply for a new eTA in that case to be on the safe side, because the cost is so low. Also, the number they ask for is your alien registration number, or A number, which will not change. The only thing that will change is the expiration date of your green card.
I believe the ETA attaches to the foreign passport and when you get a new passport, you need a new ETA.
The green card / A# is just to verify your status in the USA as there are special rules for USA permanent residents.
My partner did not have to show her American green card to Canadian immigration when she entered from the USA.