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 a. Is Santhosh required to increase his withholding or make estimated tax payments this year to avoid the underpayment penalty? O Yes b. By how much, If any, must Santhosh increase his withholding and/or estimated tax payments for the year to avoid underpayment penalties? Increase in withholding