David Scott Hamilton Bankruptcy Law Blog on Lawyers.com

Straight married couples can file bankruptcy on the same bankruptcy
petition and as such have some benefits from this, such as not having
to pay the $299 filing fees twice). As the law stands, gay couples
cannot file a joint petition, whether or not they are within a civil
partnership or legally married under state law. Bankruptcy is a federal
law and the federal Defense of Marriage Act ("DOMA") prohibits federal
recognition of this.

The Obama Department of Justice has said:

With
respect to the merits, this Administration does not support DOMA as a
matter of policy, believes that it is discriminatory, and supports its
repeal. Consistent with the rule of law, however, the Department of
Justice has long followed the practice of defending federal statutes as
long as reasonable arguments can be made in support of their
constitutionality, even if the Department disagrees with a particular
statute as a policy matter, as it does here.

However there are currently no immediate signs of this changing.
This leaves gay couples the choice of filing joint petitions and facing
joint fees, or hiring a bankruptcy lawyer with the aim of challenging
the law.