if you need a tax form that Turbotax does not support like Form 8990. You are on your own, you'll have to prepare it manually by getting the form from the IRS website and completing it. Then you have to enter the results in your tax return. Turbotax accuracy guarantee may not apply. Finally, you won't be able to e-file unless the form is specified on Form 8453 (if it's on it you can e-file and then follow the instructions for submitting the form or schedule to the IRS)
https://www.irs.gov/pub/irs-pdf/f8453.pdf
for a list of TurboTax forms supported see this s link
https://form-status.app.intuit.com/tax-forms-availability/formsavailability?albRedirect=true&product...
