Calculate your quarterly estimated tax payments for self-employment or investment income.
If you expect to owe $1,000+ in tax after withholding (self-employed, freelancers, investors, retirees), the IRS requires quarterly estimated payments. Due dates: April 15, June 15, September 15, January 15. Underpayment penalty applies if you don't pay at least 90% of current year tax or 100% of prior year tax (110% if AGI > $150k).