Every year we are interested in discovering if it's better for us to file jointly or separately. Every year I see the Turbotax instructions on how to do this....which is to fill out a complete joint tax return, but not file it.
Then you go back and start all over again, entering a separate return for myself, and then a separate return for my husband. You then manually compare the three returns. It's incredibly tedious, and we're hoping this year, after we fill out the joint return, that Turbotax simply has a button that says something like "Click here to see if filing separately would save you money."
