First, you must designate certain categories as tax-related. Click "Categories" in the source list and put a check in the "Taxable" column for any tax-related categories. You may also assign tax codes where appropriate.
Second, you must assign those categories to all relevant transactions. You may need to split some transactions and assign a tax category to one portion and another category to the remainder.
Next, you must create a "Custom" chart that includes all your tax categories. Use the button to "Add All Taxable Categories" to the chart quickly. Be sure to set an appropriate date range for the chart as well (after all, you don't want to include 2006 transactions on your 2007 tax forms!).
Finally, click the button and choose "TXF (Tax Format) File." Save the TXF file to your Desktop or any convenient location. When you run TurboTax or another tax program, it should ask you at some point to import data from another program - direct it to the TXF file you saved so that it can import your tax data.
Even if other categories are included in the chart, the TXF export will only include categories that are designated as "taxable." Make sure you have your categories set up correctly before exporting.
For more information about charts and exporting, see the end of the Chart Types: Quick Summary & Custom page.