It looks like Turbotax's choices for calculating estimated tax payments are
- 100% of your prior year's taxes owed (or 110% if your income was over a certain threshold)
- 90% or 100% of what you estimate you'll owe for the current year
- 66.667% of what you estimate you'll owe if you're a qualified farmer or fisherman
The 110% calculation is used if your AGI is greater than $75,000 for single and separate filers and $150,000 for married filing joint, so perhaps that's what it's doing for you?
More info here: https://turbotax.intuit.com/tax-tips/small-business-taxes/estimated-taxes-how-to-determine-what-to-p...
