HLO.6 Julie, a self-employed individual, is required to make estimated tax liability for the year. Her tax liability for 2020 was $25,000, and her AGI was less than $150,000. For 2021, Julie ultimately determines that her income tax liability is $18,000. During the year, however, she made the following payments, totaling $13,000. April 15, 2021 June 15, 2021 September 15, 2021 January 18, 2022 Total paid $ 4,500 2,800 4,100 1,600 $13,000 Because Julie prepaid so little of her ultimate income tax liability, she now realizes that she may be subject to the penalty for underpayment of estimated tax. a. Determine Julie's penalty for underpayment of estimated tax, if any. b. Instead, assume that Julie's tax liability for 2020 was $15,960. on Teing the for