Most progressive tax systems only have you pay the higher rated on the amount in that bracket to avoid the disincentive.

More accurately, this is a form of alternative minimum tax- a higher floor than the normal brackets specifically for those who cross a specific threshold.

That does carry a hefty incentive to play games with your accounting, and is ultimately rather foolish since the people it was really aimed at when introduced in the US shifted their income to capital gains instead.

Now, it is mostly a way to punish people for becoming upper middle class.