"Do I need to submit Form 2210 &/or pay penalty for not paying enough in estimated taxes though I paid in full the amt TT instructed me to pay last year?

When you use TurboTax, or *any* program for that matter, to estimate your next tax year's quarterly taxes, that's all it is....and *e*s*t*I*m*a*t*e. That estimate is based on your prior year's income and tax liability, since that's all the program (Or any program for that matter) has to work with. There's no way the program (or even you for that matter) can possibly "Know" how much you will earn in a quarter, before you actually earn it. But unlike any program, you can "guess" a heck of a lot more accurately than "any" program can.

Generally, if what you owe the IRS at tax filing time is more than $1000 or more than 10% of your total tax liability (whichever is *higher*) then an underpayment penalty is assessed. The 2210 is then required and the program will generate it for you. If you do the 2210 Part IV that has the potential to reduce, or sometimes even eliminate the penalty (if it wasn't already eliminated in Part I).

Overall though, and of course this is just my personal opinion, I've always held the position that "figuring" your quarterly taxes is an absolute waste of time and effort. I've been self-employed for around 15 years now and I do a simpler method that so far, has always without fail put me well within 10% of my tax liability every year. I simply send in no less than 20% of my quarterly gross earnings each quarter. Most years I get a refund and generally that refund is less than $1000. In the years I owe more, it's always been less than $1000. The end result? No penalties.