What is an "Ironclad" Prenup? 

 Posted on October 08, 2025 in Prenuptial & Postnuptial Agreements

Many engaged couples want to start their marriage on strong financial footing, but few enjoy discussing what might happen if the relationship ends. Still, creating a prenuptial agreement — often called a "prenup" — can provide peace of mind for both parties. A well-drafted prenup does not only plan for divorce; it sets clear expectations about finances, debt, and property during the marriage itself. But what makes a prenup truly "ironclad" and legally enforceable in Illinois?

At Goostree Law Group, our Wheaton, IL family lawyers help couples write solid prenuptial agreements. We focus on your goals, interests, and Illinois law. Call us today to get started.

What Exactly Is a Prenup?

A prenuptial agreement is a legal contract entered into by two people before marriage. Its main purpose is to outline how assets, debts, and financial responsibilities will be handled during the marriage and in divorce or death.

In Illinois, prenups are governed by the Illinois Uniform Premarital Agreement Act (750 ILCS 10/1 et seq.). The law sets rules about how such agreements must be made and when they are enforceable. While prenups have a reputation for being unromantic, they are actually practical legal tools that can protect both spouses.

A strong prenup can save you from expensive disputes later. It can protect future inheritance, and ensure that your financial wishes are respected by the court.

What Makes a Prenup "Ironclad" or Enforceable?

Not every prenup will hold up in court. To be considered "ironclad" (not a technical legal term), a prenuptial agreement should meet several legal requirements. Illinois courts look for these essential elements:

1. Voluntary Consent: Both parties must enter into the agreement willingly. Any hint of coercion, manipulation, or duress can make a prenup invalid. Signing right before the wedding, for instance, can raise questions about whether either spouse was pressured into signing.

2. Full Financial Disclosure: Each party must fully disclose all assets, income, and debts before signing. If one person hides significant assets, the agreement can be challenged later.

3. Independent Legal Counsel: While not legally required, it is strongly recommended that each party have their own attorney. This helps prove that both parties understood what they were agreeing to.

4. Fairness and Reasonableness: The agreement must not be unconscionable. It cannot heavily favor one spouse in an unfair or exploitative way.

5. Proper Execution: The prenup must be in writing and signed by both parties before the marriage happens.

If these criteria are met, the agreement will likely be upheld, even if one party later regrets signing it.

What Can Be Included in a Prenup?

A prenuptial agreement can cover a wide range of financial issues. Everyone’s prenup is a little different, but most have certain parts in common.

For example, most prenups say which assets will remain separate and how marital property will be divided if you divorce. Many also clarify who is responsible for certain debts. You can agree in advance whether either spouse will pay support and how much. However, a court may strike down this provision if it causes undue hardship at the time of enforcement.

Prenups are valuable tools for business owners who want to protect their company from being divided or sold during divorce. A prenup can say whether a spouse will have any ownership over a business in a divorce and, if so, what that will look like. Prenups can also outline how assets will be distributed if one spouse dies. This is done by people who have been previously married and who have children from prior relationships.

While you can decide how to handle most financial matters, Illinois law does not allow prenups to address terms about child support or custody, as those issues must always reflect the child’s best interests at the time of divorce.

When Can a Prenup Be Challenged in Illinois?

Even well-drafted agreements can be challenged. Common arguments used to invalidate a prenup include:

• If one spouse claims they were pressured into signing it or lacked time to review the agreement

• If one spouse failed to reveal significant assets or income

• If the agreement was extremely unfair when signed or would cause severe hardship when enforced

• If the agreement was not properly signed or witnessed before the marriage

For example, if one spouse signed the agreement the night before the wedding without talking to a lawyer, a judge might think that spouse was coerced into signing. Similarly, if one person concealed a major financial account, the prenup could be invalidated on grounds of nondisclosure.

How Can I Make Sure My Prenup Holds Up in Court?

Working with a good attorney is the best way to ensure your prenup will not be overturned. A family lawyer will help you in several ways. First, you need to make sure you and your fiance have provided each other with full and accurate financial disclosure. Your lawyer will help you understand what this means.

Next, your lawyer will talk to you about what is important to have in your contract. Based on your answers, your attorney will write clear, detailed terms. These should avoid one-sided provisions that invite legal challenges, but should look out for your interests.

Your attorney will also be mindful of when the prenup is written and assigned. If it is too close to the wedding, the timing of signing could suggest coercion. Finally, your attorney will work with your spouse’s attorney to make sure you both agree to what you are about to sign.

Is a Prenup Only for the Wealthy?

Absolutely not. Prenups are not just for the rich or for people with complicated estates. Anyone who owns property, has children from a prior relationship, carries significant debt, or wants to set financial expectations can benefit from one. In fact, a prenup often strengthens a marriage by lowering uncertainty and potential resentment over money.

Creating a prenup is not planning for divorce. It is planning for stability and mutual respect, regardless of what the future holds.

Contact a Wheaton, IL Prenuptial Agreement Attorney

A prenuptial agreement can be one of the most valuable investments you make before marriage. When written well, it can protect both of you and prevent certain problems in a future divorce. At Goostree Law Group, our DuPage County, IL family lawyers provide skilled counsel and personalized guidance to help couples make fair, enforceable agreements that stand the test of time.

To schedule your free consultation, call 630-584-4800 today and meet with an attorney who can help you create a truly ironclad prenup.