That’s a question better addressed to the IRS.  Their guidance, however, is clear.  No social security numbers equals no deductions and no right to claim head of household status.  There are two minor exceptions.  If your dependent was born and died in 2007 and didn’t have a social security number, you can write “died” in the space.  If you’re in the middle of an adoption of a child who is a U.S. citizen or resident and you are unable to get a social security until the adoption is finalized, you can apply for an adoption taxpayer number to use until you can get a social security number.  To do this, you need to file an IRS Form W-7A, Application for Taxpayer Identification Number for Pending U.S. Adoptions.