If you exercised Incentive Stock Options (ISO), but sold no actual stock, then you would have nothing to report on Schedule D, capital gains or losses . . . in the absence of any other stock trading activity. So, for that you won't need TurboTax Premier.
However, the exercise of ISO options does trigger a couple of tax events.
First, you will have an increase in your taxable wage income (W-2, Box 1) for the "bargain element" discount between the exercise price of your options and the market price of your company's stock. However, your employer should take care of that on your W-2 itself, and thus there is no need for TurboTax Premier for this item either.
Second, you may owe Alternative Minimum Tax (AMT) on the difference between your ordinary tax liability and your AMT tax liability on this so-called bargain element, caused by the exercise of your ISO options. To determine that amount, if any, however, you need to fill out a special Form 6251 (AMT) worksheet in TurboTax. This worksheet is not available in the Free edition of TurboTax. And while Form 6251 is available in TurboTax Deluxe, the ISO worksheet is not. The ISO Form 6251 worksheet is only offered in TurboTax Premier and TurboTax Self-Employed (also called TurboTax Home & Business).
You can read much more about the exercise of ISOs, and the tax implications thereon, including bargain-elements and the potential for AMT liability on Form 6521, Line 14, here, at the following (3) TurboTax webpages:
https://turbotax.intuit.com/tax-tools/tax-tips/Investments-and-Taxes/Incentive-Stock-Options/INF1204...
You can view what the specialized ISO / AMT worksheet looks like in TurboTax by looking at the (2) screen-capture images attached to the bottom of this answer; simply click on them to open.
So, the true answer to your original question is that in order to calculate your taxes properly (unless you wish to complete a Form 6251 and ISO AMT worksheet by hand), you will need at least the TurboTax Premier level software product.
But, you could alternatively go through a "dummy" online tax return, add your ISO exercise using the Premier product, and if it makes no difference to your actual taxes, then you could revert back to the Free program, file your taxes using that version, and not enter your ISO data at all (which would not be necessary unless there is an AMT effect).
Thank you for asking this question.
