This year, Santhosh, a single taxpayer, estimates that his tax liability will be $109,000. Last year, his total tax liability was $18,000. He estimates that his tax withholding from his employer will be $38,000. Required: Is Santhosh required to increase his withholding or make estimated tax payments this year to avoid the underpayment penalty? By how much, if any, must Santhosh increase his withholding and/or estimated tax payments for the year to avoid underpayment penalties?