Today is January 15th. That means your fourth quarter estimated tax payments are due today. It’s a postmark deadline, so if you pay by mail, download Form 1040-ES, print voucher #4, enclose your check payable to “United States Treasury” (write your social security number and “2018 Form 1040-ES” on the check) and mail it using certified mail, return receipt requested, to the address for your state. And don’t forget your state estimated tax payments (if applicable). You can also use EFTPS and IRS Direct Pay to make your payments to the IRS electronically; most states offer webpay systems, too.