Illinois couple who are in civil unions will file married returns for 2011. They will, for state tax purposes only, file either married filing jointly or married filing separately. Note that they will still file single returns for their federal taxes.
While this may be a beneficial result, it will likely also be a more expensive situation for such couples. Tax professionals will have to prepare two separate returns: A single return for federal tax purposes, and then a joint (or married filing separately) return for state purposes. Impacted individuals should expect that the cost will increase because such returns will take more time to prepare.
