Is the end of year bonus a Iron Man thing or is that something different? What requirements would be needed to get any kind of bonus?
Yes. it's an ironman thing. If you aren't on track for it now, you can't get there. This time.
Assuming it continues, it's a twice a year thing -- June and December, in which, if you make even the lowest level Ironman that month, you will get a bonus of $X amount for each month you made Ironman. The amount of bonus depends on the Ironman levels you made each month and how many months.
It's a nice extra. My only beef is that they only give you about a month and a half to clear it, which is usually not enough time at the levels I play at. But then again, I also learned painfully not to chase bonusses. I play as I usually do, maybe slightly longer, if I can, but not at higher levels. In June, for instance, I earned about half of the bonus before the time period lapsed. That, of course, is money that I wouldn't have had otherwise, and is welcome. While it's difficult to not fuss about the amount I didn't manage to clear, I figure that goes along with poker patience and discipline. Character building.