If you make estimated tax payments, the amount you owe may be affected by the law enacted on July 4. It introduces tax breaks that could shift your income tax liability. Estimated tax payments ensure that certain people pay taxes throughout the year. You may have to make them if you receive interest, dividends, self-employment income, capital gains or other income. If you don’t pay enough through withholding and estimated payments during the year, you may be liable for a penalty. Individuals generally must pay 25% of their required annual tax four times a year with Form 1040-ES (an exception may be available if your income isn’t uniform over the year). The next payment is due Sept. 15.