How is alimony calculated in Illinois?

If the court determines that a maintenance award is appropriate, the court shall order maintenance in accordance with the following guidelines:

• In situations when the combined gross income of the parties is less than $250,000 and no multiple family exists, maintenance shall be in accordance with the guidelines, unless the court makes a finding that the application of the guidelines would be inappropriate.
• The amount shall be calculated by taking 30% of the payor’s gross income minus 20% of the payee’s gross income. The amount of maintenance, however, when added to the gross income of the payee, may not result in the payee receiving an amount that is in excess of 40% of the combined gross income of the parties.
• The duration of an award for maintenance shall be calculated by multiplying the length of the marriage by whichever of the following factors applies: 0 – 5 years (.20); 5 – 10 years (.40); 10 – 15 years (.60); or 15 – 20 years (.80). For a marriage in excess of 20 years, the court shall order either permanent maintenance or maintenance for a period equal to the length of the marriage.