Tax Years That Are Supported By the Tax Planner
Because the U.S. tax code changes constantly, the Quicken Tax Planner supports two years of tax calculations: the year that the Quicken version was released plus the following year.
For example, Quicken 2017 was released in 2016, so its Tax Planner supports calculations for tax years 2016 and 2017. If you use that version's Tax Planner in 2017, Quicken displays your current (2017) data, but it will continue to use the tax calculations based on the 2016 IRS tax tables.
Keep in mind that Quicken's Tax Planner is not intended as a tax-calculation tool (that function is handled by TurboTax); instead, the purpose of the Planner is to give you a "snapshot" of your tax situation throughout the year.
Using the previous example, if you wanted to view your 2016 data in Quicken instead of 2017, click on the link for "year" in the top left and change it to 2016.