Can I file additional forms with my return, like a form 2210? can I upload additional files when I e-file?

It depends what you mean by upload. If from an outside source, then no. If you need Form 2210, you can select it from within the program.

 

IRS Form 2210 (Underpayment of Estimated Tax by Individuals, Estates, and Trusts) calculates the underpayment penalty if you didn't withhold or pay enough taxes during the tax year.

Form 2210-F is a variation if you made at least 2/3 of your gross income from farming or fishing.

We'll automatically generate a Form 2210 if your return needs it. Or you can revisit this section:

Note: You'll need your prior year tax return to answer the questions.

1. Sign in to TurboTax and open or continue your return.
2. Search for underpayment of taxes.
3. Select the Jump to link in the search results.
4. The Underpayment Penalties screen will display the penalty amount. Select Continue to review this section and make any needed adjustments.
   • Note: If you see No Underpayment Penalty, you either haven't entered your income and/or estimated tax payments yet, or you aren't subject to an underpayment penalty.

(Optional) Keep going, and when you get to the Annualized Income Method screen, answer Yes if you want to see if we can reduce the penalty.

By the way, Form 2210 won't be ready until Feb 18,

https://ttlc.intuit.com/community/forms/help/irs-forms-availability-table-for-turbotax-individual-personal-tax-products/00/26224