Taxcaster looks like it's going to file my return...asking for payment, etc. etc. when all I want is comparison of 2017 taxes to 2018 taxes. What am I missing?

[DoninGA]

TaxCaster is only a calculator.  It does not and cannot file a tax return.
Did you use this website for TaxCaster - <a rel="nofollow" target="_blank" href="https://turbotax.intuit.com/tax-tools/calculators/taxcaster/">https://turbotax.intuit.com/tax-tools/...>

[xmasbaby0]

Tax caster does not file a tax return.  You must have gotten confused.  Did you accidentally start filling out a tax return instead?  If you already filed a 2017 return it will be impossible to e-file another return even if you try.

[SteamTrain]

You probably clicked on a wrong button during your prep  (see picture below)

Stick to the main pages using the Edit selections, or the "Continue" button in the middle of the page.

...stay away from the "Start for Free" button that shows up lower down the page when you get  part-way thru the Q&A  (I've hit it accidentally a couple times myself and had to start all over)