Technically speaking, the support obligation is his and his alone.  You cannot be forced to support a child that is not yours.   However, where most innocent spouses get stung is in the bank account when funds get co-mingled.  Same applies to other assets and resources.  To avoid having your income confused with his income, you would be better off keeping your finances separate... that way funds can always be easily tracked.  You can do the same with federal income taxes.  You do have the option of filing jointly, but are not required to do so.  Since he has several things coming at him, you would be better off filing separate-- that way your income does not show up in court records.  (In enforcement and child support actions, he will be required to produce w-2's and tax returns.)  This is the basic effect on your income and taxes.  Keep in mind, however, that if he gets a big hit with back child support, that the court may order makeup payments to be garnished from his wages-- which means that more of the burden of supporting the household will be on you.  So even though you are going to be hit directly, there will be an indirect him just by way of loss of overall income.