How Is Commingled Property Addressed in an Illinois Divorce?

 Posted on June 05, 2026 in Property Division

When a couple chooses to end their marriage, they will need to address a variety of issues during the divorce process. Foremost among these is the division of marital property. All assets and debts that a couple owns together must be divided fairly and equitably. In addition to marital property, each spouse will likely have certain assets that are considered separate property, including items they owned before getting married, assets received through inheritances, and property excluded from the marital estate by a prenuptial or postnuptial agreement. 

Separate property will not be divided between spouses, and each party will be able to retain ownership of the assets they originally possessed. However, there are many situations where marital and separate property may become mixed together or "commingled." At Goostree Law Group, our St. Charles, IL divorce lawyers have represented clients in difficult property division cases for decades. 

Common Examples of Commingled Property in 2026

Illinois law presumes that most property acquired during a marriage is marital property (750 ILCS 5/503). That presumption can be difficult to overcome once the funds or assets have been blended. This is especially true when a couple has combined finances over the course of a marriage. When assets become commingled, it may be possible to trace them back to their source. If that is not possible, separate property may be "transmuted" into marital property and included in the property division process. Consider some common situations where commingling can occur.

Real Estate Property 

A home or other property that one spouse owned before the marriage will generally be considered separate property. However, if the other spouse made contributions toward the increase in value, part of that asset may be treated as marital property. For example, if both spouses used their income to make mortgage payments, the increase in equity may be considered a marital asset.

The name on a title is not always the final word. Even if only one spouse is listed on the deed, a court may still consider contributions the other spouse made during the marriage. If a spouse helped improve a home owned by the other spouse, whether by performing work or helping pay a contractor, that spouse may be able to claim partial ownership. During property division, the original owner may have to reimburse the other spouse for those contributions.

Family Businesses 

A business one spouse owned before the marriage will usually be considered separate property. However, if the business’s value rose over the course of the marriage, that increase may be treated as a marital asset. This is especially true if the other spouse invested marital funds or worked for the business directly.

Those contributions may give the non-owning spouse a claim over certain business assets. To retain sole ownership after a divorce, the business owner might need to buy out the other spouse's share.

Inheritances

Money or property inherited by one spouse is usually considered separate property. However, combining an inheritance with jointly held assets can cause it to be transmuted into marital property.

For example, suppose an inherited sum is deposited into a joint bank account. Over time, both spouses make deposits and withdrawals from that account. At that point, it may become very difficult to determine how much of the balance was ever separate property. An attorney can review the account history to identify what portion of the inheritance may still be traceable.

How Are Commingled Assets Divided in Illinois Courts?

When dividing commingled assets, an Illinois court will weigh several equitable distribution factors, such as:

• How long the marriage lasted and what each spouse contributed to the marital estate

• The value of each spouse's separate property and what they are walking away with

• Each spouse's current income, earning potential, and financial obligations

• Whether either spouse has custody of children and what that means for housing and stability

• Any agreements the spouses made, such as a prenuptial or postnuptial agreement

Once separate and marital funds are mixed, tracing the original source becomes the central challenge. A court will look at the evidence available and decide whether the separate portion can still be identified with reasonable certainty. If it cannot, the entire asset may be divided as marital property. That outcome can feel unfair, but it reflects how seriously Illinois courts treat the burden of proof on this issue.

How To Support a Claim of Separate Property in Kane County

Claiming that an asset is separate property is not enough on its own. You need documentation that clearly connects the asset to its source. The stronger your records, the better positioned you are to make that argument in a Kane County courtroom.

Start by gathering financial records from before and during the marriage. Bank statements and account histories can help show where money came from and where it went. If you received an inheritance or a gift, hold onto any supporting documents. Letters, estate documents, probate records, and written communications can all help establish what you received and when. Real estate records, closing documents, and mortgage statements are also worth keeping. These can help trace the original purchase of a property back to its source.

Keeping assets in separate accounts from the beginning is one of the best ways to protect a separate property claim. Once funds are pooled with marital money, the paper trail becomes much harder to follow. Receipts, tax returns, loan documents, and correspondence with financial institutions can all serve as useful evidence. The goal is to give a court a clear, documented path from the source to the current asset.

Contact Our St. Charles, Illinois Asset Division Lawyers

At Goostree Law Group, we regularly handle divorces with complex marital estates. Contact our Kane County, IL property division attorneys today at 630-584-4800 to schedule a free consultation.