JOINT TAX RETURNS
Under California law, the community property generally is liable for a tax debt incurred by either spouse during marriage. See Fam. Code § 910(a).
If spouses file a joint return, each spouse is jointly and severally liable for the tax due, even if only one spouse had income. I.R.C. § 6013(d)(3).
Apparently the IRS will accept a joint return signed by only one spouse, particularly when there is an accompanying statement to the effect that the spouses are in the midst of a marital dissolution and the signature of the other spouse cannot readily be obtained.