a couple of seasons ago, BB introduced a tax, called the 'Over Extension Tax'.
What teams were doing, is they were buying up big massive rosters of players with huge salaries and running their team at a loss for weeks, months, or even the whole season in order to win.
SO their tactic was - tank for a few seasons, save up a big pile of money, and then 'over-extend' themselves at some point during the season (maybe the whole season) - run their economy at a loss - but essentially they would win all their games and the finals.
It was one of the ways teams would tank-then win and promote.
In an effort to stop this, BB introduced a tax.
If your team is running at a loss (that is, your weekly economy) - you get taxed on that over-extension. at a 50% tax rate.
So for instance, if your weekly loss is $50k, then your tax would be $25k, making your total weekly loss = $75k.
This makes it much more expensive to tank and then overextend urself for a season.
You can avoid paying some or all of the tax by having 'training exemptions'. Any salary increases in a trainee (ie: you train one guy for one season, his salary goes up $20k) - that salary increase can be used as an offset against the over-extension tax.
So if we use the above example, your $25k overextension tax would be offset by $20k training exemption, thus your overall tax would only be $5k. So your weekly loss would be $50k + ($25k - $20k) - $55k.
Hope that helps!