If the taxes you owe are the result of previous years' filings made before you began divorce proceedings, and if you and your husband filed joint married returns for those years, there's nothing you can do about changing your filing status – it's too late. No matter who is supposed to pay these taxes according to your decree, you're both responsible for paying them as far as the IRS is concerned. However, if your divorce is final on or before Dec. 31 of the tax year, you have no liability for taxes due on your husband's income for that year because the IRS won't allow you to file a joint married return.
If you never filed joint married returns with your husband, you're not responsible for paying taxes due on those returns if they're assigned to your husband in your decree. Spouses always have the right to elect to file separate married returns, and if you do so, you're only responsible for taxes due on your own income. If you filed joint married returns, however, you and your husband are "jointly and severally liable" for the taxes. If your husband doesn't pay, the IRS will expect you to do so.
Changing Your Mind
You have a small window of time to protect yourself against tax liability for a jointly filed married return. Up until the tax due date, typically April 15, you can amend the joint married return to a separate married return. If you do this, you wouldn't be responsible for any taxes due on the joint return that have been assigned to your husband in your decree.
If it's too late to amend your joint returns, and if the IRS is looking to you for payment of taxes your decree says your spouse is obligated to pay, you have a few options. If you must pay the tax debt yourself, you can usually take your husband back to court to enforce the terms of your decree. The court can order him to reimburse you and may even enter a money judgment against him. You could then use the judgment to place a lien against his property for the money he owes you.
You can also appeal to the IRS for help by filing Form 8857 to explain why you feel you should not be responsible for the tax debt. Separation of liability relief allows you to separate out a portion of the taxes due, such as those that might be attributable to your own income, and pay only that. You would not be jointly and severally liable for the whole amount, but only a percentage of it. You can also apply for equitable relief if your spouse was supposed to pay the tax debt but did not. You can try to convince the IRS that it should not hold you responsible. Time limits apply, however, and the rules are complicated, so if the IRS pursues you for taxes your husband was supposed to pay, speak with an accountant or attorney.