Some time back, I asked Canon tech support about whether there was something on their retail package that could be decoded as an expiration date. I was considering purchase of what seemed to be a "too good to be true" eBay item.
IIRC, the response from Canon was "unopened tanks don't expire". That surprised me, but I have no reason to think they were being other than honest with my direct question.
However, that was about CLI-8 dye ink for my Canon 9000-2. I can't generalize to other ink they sell for other printers. YMMV, especially with non-oem ink as far as expiration dates.