I support my fiance since she's a stay at home parent.......

[DW1]

She made under $1000 last year. Does she have to file separately? She has no insurance and if I were to claim her, my fee skyrockets. Not sure what to do.

[IsabellaG]

Your fiancé can’t file a joint return with you until the year that you are married. She doesn’t have to file a tax return at all if her only income was wages of and she had gross income of less than $10,350, but she might want to file a return to get all of her withholding refunded.

You might be able to claim her as a dependent if she lived with you,  you support her, she doesn’t provide more  than half her own support, she’s not a qualifying child for another person, she doesn’t file a joint return with someone else, and she had income less than $4050.

But as you say, if she’s your dependent and she didn’t have health insurance, it would be of no advantage to claim her if your taxes go up significantly because of that. 

You have to compare the two options and choose between them.