Best Answer: If you are still married and living together (did not live apart for the last 6 months of '07) you have two filing options; married filing joint or married filing separate.
If, however, I misunderstood your question and you two did not live together during the last 6 months of '07 and you paid more than half the costs of keeping up a home for you and the child then you could also file as head of household.
Married filing joint usually results in the lowest taxes due - largest refund. but not always. If one of you had more itemized deductions and/or if your incomes were about the same, married filing separate may net you a bigger refund. You can calculate it both ways and take the route that works out best financially.
It's important to note you'll lose several important tax breaks if you file
1. You can't take the credit for child and dept care credit in most cases.
2. You cannot take the earned income credit.
3. You cannot take the education credits, the deduction for student loan interest or the tuition and fees deduction.
4. Other tax breaks will phase-out at lower income levels:
a. the child tax credit
b. the retirement savings contribution credit.
c. itemized deductions (to include mortgage interest)
d. the deduction for personal exemptions
There are others but you get the idea.
If your goal is to reduce your taxes as much as possible, figure it both ways, but married filing joint is likely your best best. If you file separately, it would be ideal for you to claim the child and the mortgage interest, property tax, etc. but that will certainly hurt your husband in terms of tax liability.