Vincent anticipates that his actual tax liability for the tax year 2017 will be $12,000 and that federal income taxes withheld from his salary will be $9,000. Thus, when he files his 2017 income tax return, he will have a $3,000 balance due. In the previous year, his actual federal income tax liability was $8,000 and his AGI was less than $150,000.

a. Is Vincent required to make estimated tax payments in 2017? Explain.

b. Will Vincent be subject to an underpayment penalty if his 2016 AGI was $175,000? Why?