79. This year, Santhosh, a single taxpayer, estimates that his tax liability will be $100,000. Last year, his total tax liability was $15,000. He estimates that his tax withholding from his employer will be $35,000. Is Santhosh required to increase his withholding or make estimated tax payments this year to avoid the underpayment penalty? If so, how much? 79. This year, Santhosh, a single taxpayer, estimates that his tax liability will be $100,000. Last year, his total tax liability was $15,000. He estimates that his tax withholding from his employer will be $35,000. Is Santhosh required to increase his withholding or make estimated tax payments this year to avoid the underpayment penalty? If so, how much