The last installment of your 2016 estimated federal income tax is due January 17, 2017. As a general rule, to avoid penalties you need to pay in the lesser of 90% of your 2016 estimated tax liability or 100% of the tax shown on your 2015 return when your adjusted gross income (AGI) is less than $150,000. When your AGI is over $150,000, you’re required to prepay the lesser of 90% of your 2016 estimated tax liability or 110% of your 2015 tax liability. What if you haven’t paid in enough? Increase your last installment to make up for the underpayment. Contact us for help with the calculation.