After my divorce I was able to file as head of household on my 1040 tax return. We lived apart for more than 6 months, even though we were still married, I had two qualifying children also. I worked full time and only earned about 18,000 per year. So even though little tax was taken out of my check I still got more of a refund than what I paid in. Those nice refund checks helped out a lot. See: http://www.irs.gov/faqs/faq-kw80.html
I have since remarried, boy I wish I could still file like that!