Your tax filing options may be more plentiful than you know, if you are single and living with someone. Presuming that the "someone" is not just your roommate, but a person with whom you potentially envision a future, you might even be able to file as a married couple. And if marriage is not quite on the horizon for you, your relationship could still qualify for some other tax benefits, on the basis of your shared experience.

Individually

To each his own, and where your living arrangements and taxes are concerned, filing just your own return may have been the only option you contemplated. Filing individually makes sense if the person you're living with is not your significant other; however, it might also make sense if you are attached. In states where common law rules, unwed people who live together for a length of time may be deemed married. If you don't hold yourselves out to be married or see marriage in the offing, filing individually is your best option. (Ref 4)

Head of Household

A spin on the unmarried filing individually theme is to file as head of household -- provided you qualify. The Internal Revenue Service allows you to file as such for additional deductions and lower tax rates if you are unmarried as of the last day of the year and you contributed more than half the upkeep of a home for the year and had a qualifying person live with you at least half of the year. The qualifying person can be your partner if you can claim him as a dependent and he meets four criteria for income, support, being a member of your household and not being a qualifying child.

Jointly as Married Couple

Whereas couples who live together don't even have to deal with the system of legal precedent known as common law if they aren't seeing wedding bells in the distance, couples who lean in the connubial direction may need common law on their side to be able to file jointly as a married couple. Without legal recognition of your relationship as equivalent to a bona fide marriage, you would not be able to do this and only be able to file as an individual unit. Joint filing not only simplifies your paperwork, but it also allows you to take advantage of earned income tax, child and education credits.

Separately as Married Couple

If common law does recognize you as a married couple, you would have the same filing options that a married couple would: You could file as married filing separately or married filing jointly. While the first may not entitle you to the same array of credits and deductions as the latter, benefits are still numerous: By separating your returns, you may be better able to meet the eligibility requirements for certain deductions, such as medical bills exceeding 10 percent of your income. Also, any pending judgments on your partner's return would be kept apart from your own, thus protecting your own assets.

A Word on Same-Sex Partners

While the IRS and U.S. Department of Treasury announced in August 2013 that legally married same-sex couples would be treated as married for federal tax purposes, the issue of taxation for unmarried cohabitating same-sex couples remains murky. As of the time of publication, the government does not acknowledge same-sex civil unions or registered domestic partners as married, nor do all states that recognize common law marriage as real marriage confer married status automatically to same-sex couples in their jurisdiction. For these couples, single filing may be among the only options.