Start with the maintenance agreement and judgment
Section 510(c) expressly recognizes a qualifying written agreement set forth in the judgment or otherwise approved by the court. Bring the complete marital settlement agreement, dissolution judgment, and later maintenance orders to your consultation. A summary stating that maintenance lasts a certain number of years is not enough to evaluate the actual termination provisions.
Ask counsel to identify what the documents say about cohabitation, remarriage, modification, and termination. Those concepts should not be treated as interchangeable. Also identify any pending review date and any income-withholding order. The goal is to determine which obligation is disputed and which documents control it.
A cohabitation case is not simply a new calculation of monthly support. Our Illinois maintenance calculator estimates guideline amounts; it cannot decide whether a relationship meets section 510(c).
What does a resident, continuing conjugal relationship mean?
Illinois appellate opinions use the phrase de facto marriage to describe the relationship required for this maintenance rule. In practical terms, the court is looking for a marriage-like partnership, not merely an intimate dating relationship.
The person asking to terminate maintenance must prove the qualifying relationship by a preponderance of the evidence. That means showing it is more likely than not. Once the required showing is made, the recipient must respond with evidence that the relationship is not of that character. A disputed allegation alone does not shift the burden. See In re Marriage of Saunders, 2024 IL App (3d) 230151, paragraph 17, and In re Marriage of Culm, 2025 IL App (1st) 240566, paragraph 50.
Courts commonly consider six nonexclusive subjects: the relationship's length, time spent together, shared activities, interrelated personal affairs, vacations, and holidays. This is often called the Herrin factors analysis. It is not a scoring system. A dinner, vacation, and holiday photograph can fit several categories without proving a marriage-like partnership. Saunders, paragraphs 20-24.
The word conjugal does not require proof of sexual intercourse. Courts examine the marriage-like character of the relationship; a sexual-history inquiry does not replace that analysis. See Miller, 2015 IL App (2d) 140530, paragraphs 53-57.
The most useful preparation therefore explains ordinary life. Where does each person actually live? How do they organize household responsibilities? What commitments have they made? Are their finances and family lives integrated? What changes would be required if they separated? These questions help organize the evidence; no single answer guarantees an outcome.
Four published opinions show why context matters
Miller in 2015: a long dating relationship was not enough
In In re Marriage of Miller, 2015 IL App (2d) 140530, the appellate court reversed termination and remanded. The couple had a lengthy relationship involving weekends, trips, and a shared golf membership. The court distinguished those activities from a deeper mutual commitment and material partnership. Separate living arrangements, limited shared daily life, and the lack of significant combined resources mattered. Paragraphs 61-68.
The lesson is not that a dating couple can safely spend a particular number of nights together. The opinion rejects counting activities without examining their depth. A relationship can be emotionally important and still fall short of the statutory standard.
Saunders in 2024: recurring overnights did not establish a shared life
In Saunders, the trial court terminated maintenance after a bench trial. The appellate court reversed. The couple had spent substantial time together, including overnight visits, but maintained separate households and largely separate personal affairs. Neither had keys to the other's home, they had not combined finances, and the record did not establish the deeper partnership required. Paragraphs 22-24, 35-39.
This result depended on the complete record. It does not create an approved overnight schedule or make shared keys a mandatory element of cohabitation.
Miller in 2024: separate finances did not prevent termination
A different In re Marriage of Miller, 2024 IL App (3d) 230098, reached the opposite result. The majority reversed the denial of a termination petition and remanded. Although the couple had separate finances, their lives and families were substantially integrated. The partner's mother stayed in the recipient's home for most of a summer, and the couple participated extensively in each other's family activities. Paragraphs 62-69, 80-85.
The majority found a de facto marriage while the relationship lasted. A dissent would have upheld the trial court's denial. The majority's holding shows why separate accounts or a later breakup do not automatically defeat a claim. It does not make family visits alone sufficient.
Culm in 2025: the residential requirement still matters
In Culm, a Cook County case, the First District affirmed denial of a termination petition. The court emphasized that the couple never lived together or planned to, while recognizing that separate residences are not invariably dispositive. It also examined the relationship's interruptions, limited integration, and separate finances. Paragraphs 53-59, 62-66, 73-80, 100-103.
For someone comparing cases online, the important distinction is the combination of facts. Culm does not erase the separate-residence cases; it explains why the absence of a genuinely shared daily life can be a significant obstacle to proving cohabitation.
When does termination take effect, and can payments be recovered?
Under the current section 510(c), the obligation terminates by operation of law on the date the court finds qualifying cohabitation began, and the paying spouse is entitled to reimbursement for maintenance paid from that date forward. That can precede the filing date. The court must still determine the relevant facts and date; a party's suspicion is not a judicial finding. 750 ILCS 5/510(c).
This makes the timeline important for both sides. Preserve payment records and identify when a dating relationship allegedly became something different. The date of a first date, first overnight, lease signing, and actual household change may be different. Ask your attorney which date the evidence can support and how any requested reimbursement should be calculated.
Do not choose a retroactive date yourself and deduct that amount from current payments. Obtain advice about seeking a court determination, addressing withholding, and documenting the requested accounting. A recipient facing a claim should likewise prepare for the possibility of a reimbursement request rather than considering only next month's payment.
Hypothetical 1: weekend dating with separate households
Suppose Jordan receives maintenance and dates Sam for two years. They spend some weekends together, take two vacations, and attend family celebrations. Each maintains a functioning home, pays their own household expenses, and manages ordinary daily responsibilities separately. Neither has promised ongoing financial support to the other.
Those facts raise questions worth reviewing, but they do not automatically establish cohabitation. An attorney would ask whether the apparent independence reflects how the couple actually lives. A vacation receipt tells only part of the story. This example illustrates the distinction discussed in the 2015 Miller opinion; it does not predict a court's decision or create a safe number of overnight visits.
Hypothetical 2: a shared household without a shared bank account
Suppose Taylor receives maintenance and moves into Alex's home. Over time, they organize daily meals and household work together, share housing costs, care for each other during illness, and consistently present their household and children as one family. They maintain separate checking accounts.
That arrangement deserves careful review for potential section 510(c) termination. Separate accounts do not answer whether the two operate as a marriage-like partnership. An attorney would examine the actual commitments, residential history, and supporting evidence, as well as the maintenance agreement. The 2024 Miller opinion illustrates the importance of substantial personal and family integration, although its facts differ from this hypothetical. Neither example substitutes for reviewing an actual case.
A practical evidence checklist for either side
Prepare a short, dated chronology and a separate folder of existing records you may lawfully possess. Include both helpful and unfavorable information. Useful consultation materials may include:
- The controlling documents: the judgment, settlement agreement, maintenance orders, pending petition, and scheduled court dates.
- Payments: a ledger showing each maintenance payment, its date, and the corresponding bank or payment-service record.
- Residence: relevant leases, ownership records, household correspondence, and a clear explanation of actual living arrangements.
- Household responsibilities: records or firsthand knowledge concerning expenses, household work, caregiving, and routine access to the home.
- Financial commitments: relevant shared debts, purchases, beneficiary arrangements, or transfers, with an explanation of what each transaction represents.
- Personal and family life: lawfully available records of trips, holidays, and family activities, including whether the parties ordinarily participate together or separately.
- Witnesses: names of people with firsthand knowledge and a brief description of what each actually observed.
- Contrary facts: breaks in the relationship, separate daily routines, temporary stays, and records that correct mistaken assumptions.
This is a preparation aid, not a list of documents every litigant must produce. Before collecting sensitive records or asking other people for documents, discuss relevance, access, and the proper process with counsel. A spreadsheet of accusations is less useful than a short chronology that distinguishes an observation from an inference.
For example, note that a vehicle was present at a particular time rather than claiming its owner lived there. Record what you know about a transfer rather than labeling every payment financial support. Give your attorney the underlying material so the proposed explanation can be checked.
Gather evidence lawfully and preserve its context
Do not access someone else's email, banking, device, private social-media account, or location data without lawful authority. Do not install trackers or monitoring software, trespass, impersonate another person, or recruit children to investigate a parent's relationship. Bring the concern to your attorney and discuss lawful ways to obtain relevant evidence.
Formal discovery can include document requests, written questions, and depositions. Courts can limit abusive or disproportionate requests and protect privileged information. Illinois Supreme Court Rule 201(a)-(c) supplies those general boundaries; Rule 214(a)-(c) addresses requests to another party for documents and electronically stored information. Your lawyer can identify the correct process for third-party records.
For a public post or a message you received, preserve the original material and the surrounding context. Keep the account name, date, available URL, and full conversation where available. Do not edit the original image or delete messages that appear unhelpful. Explain how you obtained each item.
Authentication is a separate requirement: there must be sufficient evidence that an item is what its proponent claims. See Illinois Rule of Evidence 901(a), (b)(1), and (b)(4). An authentic photograph can still leave the central question unanswered. Showing a couple together does not necessarily show how their household works.
What happens after someone raises a cohabitation claim?
A typical contested matter involves reviewing the existing order, filing and giving proper notice of a termination request, exchanging relevant evidence, and presenting disputed facts to the court. The published cases above arose from petitions and trial-court findings, not from a paying spouse simply declaring that support had ended. The precise filings, service requirements, hearing schedule, and discovery plan depend on the existing case and court orders.
If you are seeking termination, focus the request on the relationship and a supportable start date. If you are defending, address the actual allegations with records and testimony. Avoid relying on a general statement that you are only dating when the other side has identified specific household facts. Equally, the person seeking termination should not assume that describing two people as a couple proves the case.
Before retaining an investigator or pursuing extensive discovery, discuss the likely cost, the remaining maintenance obligation, the evidence already available, and the issues that genuinely need proof. Review our maintenance attorney cost guide as a starting point, then obtain a case-specific explanation of fees and scope.
Does the January 2027 amendment change this rule?
This article addresses Illinois law in effect on November 3, 2026. The official section 510 page displays both the current text and a version amended by Public Act 104-733, effective January 1, 2027. That future amendment changes child-support provisions but leaves subsection (c)'s cohabitation and reimbursement language unchanged. Do not apply future child-support procedures to a current maintenance dispute. See Public Act 104-733, sections 5 and 99.
Talk with a Chicago maintenance attorney
Chicago Family Attorneys offers a free initial consultation for people seeking to hire an attorney. If you are concerned about paying maintenance after cohabitation, defending a termination request, or understanding an agreement before changing your living arrangements, bring the order and a concise timeline. Our Chicago divorce attorneys can discuss whether the matter fits the firm's services and what representation would involve.
The free initial consultation does not make future representation free. Fees, scope, and any engagement are confirmed separately. No particular termination date, reimbursement, or result is guaranteed.
Call 312-965-5618 or request your free initial consultation.
This article provides general information, not advice for a particular case. Updated November 3, 2026.