Today is the due date for the fourth installment of estimated taxes for 2021 for calendar-year corporations. C corporations generally must make estimated tax payments for the year if they expect their income tax minus tax credits to be $500 or more. Payments must be made electronically through EFTPS.gov or via a tax professional, financial institution, payroll service, or other trusted third party that deposits taxes electronically. S corporations make estimated tax payments only in certain special situations. #IdeaoftheDay