Free Illinois Postnuptial Agreement Template

An Illinois postnuptial agreement is a written contract spouses sign during the marriage about property, debts, and support. Notably, Illinois’s divorce statute mentions postnuptial agreements by name.

A Postnup Can Define Non-Marital Property

Non-marital property includes property excluded by valid agreement of the parties, including a premarital agreement or a postnuptial agreement (750 ILCS 5/503(a)(4)). Everything else acquired during the marriage generally counts as marital property.

Courts Also Weigh the Agreement

When dividing marital property in just proportions, a court considers a list of factors. That list expressly includes any prenuptial or postnuptial agreement of the parties (750 ILCS 5/503(d)(7)).

Valuation Dates Can Be Agreed

Courts value property at fair market value. The valuation date is the date of trial or another date the parties agree on or the court orders (750 ILCS 5/503(k)).

Transfers Between Spouses Are Presumed Marital

Illinois presumes property acquired after the wedding is marital. That presumption also covers non-marital property one spouse moves into co-ownership with the other. To overcome it, a spouse needs clear and convincing evidence. For example, they can show a transfer was for estate or tax planning rather than a gift (750 ILCS 5/503(b)(1)).

Yes, the statute allows it. Illinois sets default rules for commingled marital and non-marital property, but they apply unless otherwise agreed by the spouses (750 ILCS 5/503(c)).

Those defaults also matter in everyday life. Under them, contributed property that loses its identity transmutes into the receiving estate, while a traceable contribution can earn reimbursement. So if you plan to mix an inheritance with joint savings, your Illinois postnuptial agreement can set its own rule for that money instead.

Put an Illinois postnuptial agreement together in this order:

1. List non-marital property. Name each asset you intend the agreement to exclude.
2. Flag mixed accounts. Note where marital and non-marital money already overlap.
3. Choose commingling rules. Decide whether to keep the statutory defaults or agree on your own.
4. Record the purpose of transfers. If one spouse adds the other to a title for estate or tax planning, say so in writing.
5. Exchange full financial information before anyone signs.
6. Sign and date the final version, then keep copies with your financial records.

Focus on what Section 503 actually turns on:

• Excluded property — each asset the agreement treats as non-marital
• Commingling terms — your own rule for mixed funds and contributions
• Title transfers — the stated reason for any change in ownership
• Maintenance terms — anything agreed about spousal support
• Signatures and dates — from each spouse