You can make quarterly estimated tax payments or you can use Step 4 Line (c) on the W4 to request additional withholdings from your paycheck for the self employment income. You will need to determine an estimated self employment income when you complete the Tax Calculator . The tool will help you determine what amount to list on Step 4 Line (c) as the additional withholding.
Keep in mind that if you should continually monitor the self employment income so that you are accurately withholding. The W-4 can be updated as often as necessary to adjust for changes in income.
