No, in fact once you are divorced, you are not permitted to file jointly since you are no longer married. Prior to a divorce, however, it may be in the best interests of both of you to consider filing a joint return since you both might save money by doing so. You should consult an accountant to make this evaluation. Of course, filing a joint tax return with an estranged spouse can be difficult and requires a good degree of cooperation. It also requires an agreement as to how the refund (or obligation) will be shared between the two of you.
