The best thing to do is to decline Turbotax's offer to calculate a penalty, and let the IRS send you a bill after you pay the taxes. The calculation is almost always off by a few dollars and you end up getting a bill anyway.
Plus, when you get the bill, you can apply for an abatement if it is your first time. (Interest can't be abated, though.)
Abatement https://www.irs.gov/businesses/small-businesses-self-employed/penalty-relief-due-to-first-time-penal...