I just don't understand how I was able to e-file my 2019 tax return with the QBI deduction.
See Revenue Procedure 2019-38 at https://www.irs.gov/pub/irs-drop/rp-19-38.pdf
Section 4 states, "This revenue procedure applies to taxable year ending after Dec 31, 2017"
So for all I know, if you did take the QBI on the 2019 tax return, you "may" get an "audit by mail" on it in the future where you're asked to provide a signed statement. But I seriously doubt that will happen. Still, never say never. The fact the IRS accepted your 2019 tax return via e-file without a signed statement is an IRS issue, not a TurboTax issue. It's the IRS that accepted your 2019 tax return "as filed", and not Turbotax.
Where in the IRS code or instructions does it say it has to be manually signed?
Section3.03(D) states, "The taxpayer or RPE attaches a statement to a timely filed original return (or an amended return for the 2018 taxable year only) for each taxable year in which the taxpayer or RPE relies on safe harbor."
