Problem: Ren is an employee of NERD Group. His income is going to increase substantially in the current year because he is going to do contract work outside of his normal employment. In order to avoid penalties for underpayment of tax, Ren will be making estimated tax payments. What subsection of the Internal Revenue Code discusses the number of required installments and the due dates for each of the installments? How many installments should be made and what are the required due dates?