Originally Posted by thijsseh

It depends on what J bucket you are currently in (if you started from Y Flex it’s probably J Flex, but the 50K miles sort of threw me as that suggests a Y Flex+ to J Flex+ upgrade). The miles required is available in the mileage calculator (under ‘Loyalty’ on the website). I think this will only work on an ‘on board’ upgrade as the official rule is that you can only upgrade one cabin with miles. The ‘on board’ workaround is well known (but AFAIK not published), whether or not it works at the check in desk I simply don’t know. If you try, can you please let us know the outcome. Such data points are helpful for others.