Since you mentioned additional tax, did it mention either Schedule 2 or Schedule 4?
Here's how to look at your actual Form 1040 and Schedules 1-6 to see what entries are requiring an upgrade:
With your return open, go to the left menu column and click on TAX TOOLS, then TOOLS.
In the Tools window choose "View Tax Summary."
At the Tax Summary screen go back to the left menu column and click Preview Form 1040.
That will open the Form 1040 Worksheet and the Schedules 1-6.
Scroll down to view the Schedules.
If you can't use regular Free Edition, there is another free product you may be able to use that can handle all forms with no upgrades. It is called "TurboTax Free File Program" and is at a different website.
You have to meet only ONE of these qualifications:
1) 2018 AGI of $34,000 or less
or
2) Eligible for EIC (earned income credit)
or
3) Active duty military including Reservists/ National Guard with military W-2 and 2018 AGI of $66,000 or less
See this FAQ for more info:
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If desired, here's how to switch and start over in TurboTax Free File Program.
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/2026912-how-do-i-switch-to-turbotax-free-file-program">https://ttlc.intuit.com/questions/2026912-how-do-i-switch-to-turbotax-free-file-program</a>
NOTE: If you switch to Free File Program by that method, and find out later you don't qualify, you won't be able to go back to regular Online TurboTax in that same account. So instead of switching that way, if you wish you could start a new account (User ID) at the Free File Program website, which would maintain the option of returning to the other Online TurboTax account, if necessary.
TurboTax Free Edition (and TurboTax Live Basic) are intended for taxpayers with very simple returns that can fit on the new 1040 form without any schedules.
If we detect that your tax situation requires expanded coverage, like deductions for owning a home or self-employment income, we'll prompt you to upgrade to a version that supports the forms you need so we can maximize your tax deductions and ensure you file an accurate return.
Depending on what your tax situation was last year, you might need to use new tax forms to claim the same deductions, credits, or forms of income. Some of the situations that are now in TurboTax Deluxe and TurboTax Live Deluxe, instead of in Free Edition, include:
Go here for more info on which forms are included in TurboTax Free Edition.