LdiJ:If the return was accurate, then there is
little to no chance that a judge in a divorce
case now, 5-6 years later, will address that.
Too much time has passed.
Perhaps. But, as a lawyer, I can tell you this–it's easy to include the claim along with everything else in the property division. Since the lawyer has to argue the property division anyway, adding this shouldn't add much, if anything, to the cost of litigation. Depending on the applicable state law (and we don't know the state here) and the amount at issue, a judge might do something about that. How hard you'd fight would also depend on those two factors. But it's probably worth making at least one stab at it. If he tries and the judge doesn't bite, well, at least he tried. You never know; I've seen judges include all kinds of things you might think were too old or otherwise beyond arguing in property division. Note I didn't say that the poster would succeed, only that in the case of an accurate joint return where he didn't file anything separately, this would likely be his best avenue, uncertain though it may be, to redress the problem.
LdiJ:However if the return was inaccurate, and the
IRS has assessed additional tax and
penalties/interest plus the tax are
outstanding, then the judge in the divorce
definitely could address that.
I didn't address this situation, of course, so your disagreement cannot be about this. Yes, the judge could potentially take that into account in the divorce. Moreover, in that case the poster also can pursue the remedy of filing his own return and reporting the false joint return to the IRS. Again, depending on the amount at issue, it may well be worth doing both.