Hi, my fiancé and I moved in together in mid June 2008. We both pay 1/2 of the household bills. I have 2 dependent children that live with me. I divorced (05/08), and suppport my kids without child support. My fiancé has 2 children he has joint custody of, but his ex will be claiming them on her taxes. His children spend less than 50% of their time at our house. His divorce was final in October 2008. My question is who can claim head of household, or does on claim single? How do we do this??

If you both pay half the bills, I am going to assume that you both work, and that you both earn more than $3400 - correct? In that case neither of you is a dependent of the other. Since your fiancé is not the custodial parent of his children, he can not claim them as dependents (unless his divorce decree says otherwise). So it looks to me like your fiancé files as single with no dependents, and you file as single with 2 dependents, or head of household but ONLY IF you paid more than half the cost of upkeep of the home for the year. Your fiancé can't file as Head of Houshold, as he has no "qualifying relatives" living with him. The rules are spelled out in Pub 501:

http://www.irs.gov/pub/irs-pdf/p501.pdf

What ebaines says is absolutely correct!

However, I suspect that you may not have covered all the relevant variables in your tax equation.

For this reason, RUN, don't walk, to your nearest experienced tax professional and have him/her prepare BOTH of your returns to make sure you file correctly and legally.

Another factor to consider is your state's legal definition of marriage. Some states allow couples living together to be considered married under common law, which is recognized by the IRS as a valid marriage and would thus allow you and your fiancé to file Married Filing Jointly.

My son is 26, he lives with me, but I can't claim as a dependent because he works and claim himself. Can I file as head of household, even thought I don't have dependents to claim?

my son is 26, he lives with me, but I can't claim as a dependent because he works and claim himself. Can I file as head of household, even thought I don't have dependents to claim?

To file as HoH you must be able to claim an exemption for your son. If he made more than $3650 you can not claim an exemption for him, even though he lives with you. Plus - if he already filed and did not indicate that he is claimed as a dependent by someone else (namely you) then you should not claim him.