Is there a reason you don't want to use Married Filing Jointly (being she married him while he was in jail I am assuming they still see each other)? Also did he not make any income while in jail? If he had a job, that income is usually taxable.
I haven't heard anyone get 'single' status while married unless you mean Married Filing Separate (which is a definite option), Head of Household could become an option with kids...
No reason other than I wasn't sure if him being in jail complicated things? She said he did not have a job in jail last year so did not make any money.
I think I mistook 'single' for 'head of household', which I'm not sure what the difference is.
From about.com:
Married taxpayers may be eligible to file using the Head of Household filing status if your spouse did not live with you during the last six months of the year and your home was the main home of your child for more than half the year. Here's what the IRS has to say:"You may be able to choose head of household filing status if you live apart from your spouse, meet certain tests, and are considered unmarried.... This can apply to you even if you are not divorced or legally separated. If you qualify to file as head of household, instead of as married filing separately, your tax may be lower, you may be able to claim the earned income credit and certain other credits, and your standard deduction will be higher. The head of household filing status allows you to choose the standard deduction even if your spouse chooses to itemize deductions." (From IRS Publication 501, "Married Filing Separately")