Is there a Low Income Exemption for Dependents?

Would a 30 year old dependent who has no income still qualify for the no tax return exemption? As far as the marketplace is concerned this person is lumped in with the household income. Is this also the case with the automatic exemption? If a 30 year old dependent still qualifies for this exemption how does one fill out the tax form? The options on tax forms do not include this exemption in the check boxes.