Because of the differential, it shouldn't be too brutal unless you or your partner's income is significantly higher than last year.

This is the sort of basal logic that is used to think about tax scales (AKA brackets in the US) in the first place because the fear of being brutally taxed is what keeps people from leaning in to side income, small businesses, etc. However, a small interest bearing 'wine and cheese' fund sounds amazing.

If Medium pay is just for fun, I would reserve it for the year in some kind of high yield account and then use the funds after taxes are paid out. That way you can convert your hot takes into relief during tax time.

Are you going for the 10-year permanent residency visa? Good luck!