Estimated tax payments are usually due on April 15, June 15, September 15, and January 15 of each year, or the following Monday if the 15th falls on a Saturday or Sunday. If you earn your income fairly evenly throughout the year and you make estimated tax payments, you generally pay one-fourth of your tax liability by each estimated tax due date. If you receive your income sporadically or seasonally, it is possible to use an annualized income installment method. Using this method, you're required estimated tax payment for each quarter is the amount of tax you would owe for the quarter if you continued to earn income all year at the rate you have thus far.
Money can help you set up regular quarterly tax payments. However, if you need to use the annualized income installment method, see your tax professional or read IRS Publication 505, Tax Withholding and Estimated Tax, on the IRS Web site.