How do I compute self employment taxes when I have another job as well?

Marjory Stromme: No, because your tax rate on your se income basically starts where your other income leaves off, so it all has to be taken into account to estimate the tax on the additional income.

Christy Tirabassi: Your clients will never "take out taxes" because you are not an employee to them. Yes, you can pay estimated tax on self-employment earnings. When you file your tax return, you include ALL income on it - your "W-2 job" and your self-employment income.