You can be considered unmarried if you maintain separate legal households and do not share residences. Therefore 1 can file HOH and the other can file as single or if the other has kids in their home can also file HOH. I know this for a fact and my brother in law has been filing that way for years. This can be due to legal seperation or truly married people not living together and maintaining separate homes. The link is an exception to the general rule that you must do what your spouse does.
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