I have filed my 2016 taxes, how do I estimate taxes for coming year to determine how much if any I need to prepay

[JohnR1]

Yes - TurboTax can help you calculate both your federal and state estimated taxes for next year:

Please see the following TurboTax FAQ, "Can TurboTax calculate next year's federal estimated taxes?":

https://ttlc.intuit.com/replies/4242911

Please also see the following TurboTax FAQ, "Can TurboTax calculate the estimated payments for next year's state taxes?":

https://ttlc.intuit.com/replies/3301735