Look at your Schedule 2, Part II, Other Taxes.
Or, look at Form 1040, Line 23, for Other Taxes, including Self Employment Tax.
If you want to use a simple method for annualizing your income, take your yearly income and divide by 12. Annualizing is a method to help you budget your tax payments throughout the year.
Here's more detailed info on Form 2210.
@barbara-stefl
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