Illinois law establishes a standard formula for the calculation of spousal support. This applies as long as the parties’ combined gross income is under $500,000 and the person paying support does not have child support or maintenance obligations from a prior relationship.

Basic Formula for Calculating Illinois Spousal Support

Here’s how the formula works in Illinois:

  • Calculate 33 and 1/3% of the payor’s net annual income
  • Subtract 25% of the payee’s net annual income

This is the amount of maintenance that is due. However, the amount the payee receives cannot exceed 40% of the combined net income of the two parties.

Formula for Calculating How Long Spousal Support Lasts

Illinois also uses a standard formula to calculate the duration of spousal support. Support is equal to a percentage of the length of the marriage. Here are the percentages:

  • 20% if married less than five years
  • 24% if married five years
  • 28% if married six years
  • 32% if married seven years
  • 36% if married eight years

The formula continues, increasing by 4% per year of marriage until the couple has been married for 20 or more years. For marriages of such a long duration, the court may order either permanent maintenance or maintenance that lasts the same duration as the marriage.

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Last Update: June 18, 2024