Here's an example: In the Capital Gains Estimator, you propose a sale that yields a short-term capital gain of $5,000. If you use your Tax Planner rates and data, the Estimator not only calculates the tax for this particular sale (for example, $1,400), but it also informs you that this sale might increase the tax due at the end of the year from $1,000 to $2,400 and might place you in a higher tax bracket (moving you from the 28th to the 33rd percent bracket).
If you don't use the Tax Planner rates and data, but instead select the standard rates of 28 percent for short-term and 15 percent for long-term gains, the Capital Gains Estimator calculates your federal tax on the same short-term capital gain of $5,000 to be $1,400, but has no knowledge of any tax liability currently tracked by the Tax Planner. It can't inform you of an increase in total tax due, or that the proposed sale could place you in a higher tax bracket.