I take care of children for a living and the person paying me wants to claim the money she pays me in her "flexible spending" for her taxes. I would like her to take taxes out of my income so that I can still get a refund at the beginning of the year instead of owing taxes. What does she need to do to take taxes out of my check?

You are self-employed, so the responsibility for pre-paying your taxes (which is what employers are doing for their employees) RESTS with you.

It is actually easily done with a quarterly estimated tax return (Form 1040-ES). Any competent tax professional can do this for you, and, more than likely, you can di it yourself if you simply download the instructions from www/irs/gov and read them.

It is NOT rocket science!