The ‘Rate Progression’ graph is useful to see how your next dollar will be taxed … but it would also be very useful to see how your last dollar was taxed. Maybe you just crossed a tax rate transition, but you have no visibility in the ‘Rate Progression’ graph because it only looks to the right, not to the left.

The ‘Effective Brackets’ bar charts does have this information, but it would be nice to see it in the ‘Rate Progression’ graph as well.