When I marry, will my spouse's ex-wife be able to increase the alimony she receives based on the addition of my salary?

The traditional method of calculating child support of the non-custodial parent excluded the income of the new spouse.  However, the Illinois Courts have interpreted the term "financial resources" in dealing with the issue of funds available for college and new spousal income.

"In In re Marriage of Drysch, 732 N.E.2d 125 (Ill. App. Ct. 2000) a college contribution case, the Illinois court interpreted the statute’s definition of "financial resources." One of the factors considered when dividing college expenses is the financial resources of each party. The appellate court, citing Black’s Law Dictionary, defined resources as " ‘money or any property that can be converted to meet needs’ as well as the ‘available means or capability of any kind.’ " The court concluded that by using the word resources rather than a more narrow term, such as income or salary, "We believe that the legislature intended that the trial court consider all the money or property to which a parent has access. This may include that parent’s income, her property and investment holdings, as well as money or property that could be available to her through her new spouse." 732 N.E.2d at 129.

While Drysch involved college expenses, it defined "financial resources," which is the same term contained in the Illinois Child Support Statute, so the result should be the same in a child support case. Other case law in Illinois suggests that the income and assets of a new spouse can be considered in child support cases."

As for the advantages of filing your taxes separately, ask a professional in your area.