How do I eliminate the underpayment penalty in TurboTax if 2024 was the very first year I have had income? The lesser of zero (2023 taxes) and 100% of 2024 taxes, is $0.

You could still owe an underpayment penalty, even if you had no income in the prior year.

Per the IRS, you may avoid the Underpayment of Estimated Tax by Individuals Penalty if:

• Your filed tax return (for the current year) shows you owe less than $1,000 or
• You paid at least 90% of the tax shown on the return for the taxable year or 100% of the tax shown on the return for the prior year, whichever amount is less. If your adjusted gross income (AGI) for 2023 was more than $150,000 ($75,000 if your filing status for 2024 is married filing separately), substitute 110% for 100%.

Since you had no income last year, the second bullet point would not apply to your situation since it says, "whichever is less". However, the penalty will still be assessed if you owe more than $1,000 for 2024.