How do you pay income tax?

The IRS will sent you a form. If they don't you can pick up a form 10 40 at the post office.

Fill it out or get a CPA to fill it out for you if you have a complicated business. Then mail in a check. You may also have to send in quarterly estimated payments. Also you may have had income taxes deducted from your pay if you are not self employed. That's what they like to call withholding tax.

PS you may also have have to pay FICA (social security) taxes.

One more thing don't forget the AMT. Alternative Minimum Tax.