To avoid interest and penalties, you must make sufficient income tax payments long before your April filing deadline through withholding, estimated tax payments or both. The third 2018 estimated tax payment deadline for individuals is Sept. 17. If you don’t have an employer withholding tax from your pay, you likely need to make estimated tax payments. But even with withholding, such payments can be necessary if you have more than a nominal amount of income from self-employment, investments, alimony, awards, prizes or other sources. Contact us to learn more.