A prenup for a business owner in Michigan is a written, notarized contract under Mich. Comp. Laws § 557.28 that defines a company as separate property before marriage. Michigan enforces these agreements, but the 2017 Allard v. Allard ruling lets courts invade separate property in narrow circumstances, so drafting precision is critical.
Michigan is an equitable distribution state, not a community property state, which means courts divide marital property fairly rather than equally. For entrepreneurs, this creates both opportunity and risk: a well-drafted prenuptial agreement can shield an LLC, S-corporation, or partnership interest, but business appreciation driven by your effort during the marriage can become marital property absent clear contractual language. This guide explains how a prenup business owner Michigan strategy works, what the Allard decision changed, and how courts value closely held companies.
Key Facts: Prenups for Business Owners in Michigan
| Item | Michigan Requirement |
|---|---|
| Filing Fee (divorce) | $175 (no minor children) / $255 (with minor children), per Mich. Comp. Laws § 600.2529 |
| Waiting Period | 60 days (no minor children) / 180 days (with minor children) |
| Residency Requirement | 180 days in Michigan + 10 days in filing county, per Mich. Comp. Laws § 552.9 |
| Grounds | No-fault: breakdown of the marriage relationship |
| Property Division Type | Equitable distribution (not community property) |
| Governing Prenup Statute | Mich. Comp. Laws § 557.28 |
As of June 2026. Verify all fees with your local circuit court clerk before filing.
Are Prenuptial Agreements Enforceable in Michigan?
Yes, prenuptial agreements have been legally enforceable in Michigan divorce cases since 1981, governed by Mich. Comp. Laws § 557.28. A Michigan court will enforce a prenup if it was signed voluntarily, both parties made full financial disclosure, and the terms were fair when made and remain fair at enforcement. These three pillars determine whether your business protection holds.
Michigan courts apply a clear validity test established in the case law: an antenuptial agreement is enforceable unless it was obtained through fraud, duress, mistake, or misrepresentation, or unless there was nondisclosure of a material fact. A fourth ground exists for setting aside a prenup years later: enforcement may be denied if facts and circumstances have changed so significantly that enforcement would be unfair and unreasonable, but only if that change was uncontemplated and not reasonably foreseeable when the parties signed. For a business owner, this means a company's predictable growth should be addressed in the agreement itself, because foreseeable success is not a basis for later invalidation. Drafting the agreement to anticipate business expansion strengthens enforceability and reduces the risk that a judge treats appreciation as an unbargained-for windfall.
What the Allard v. Allard Ruling Means for Business Owners
In Allard v. Allard, 318 Mich App 583 (2017), the Michigan Court of Appeals held that parties cannot, through an antenuptial agreement, deprive a trial court of its equitable discretion to invade separate property under Mich. Comp. Laws § 552.23 and Mich. Comp. Laws § 552.401. This ruling directly affects every business owner relying on a Michigan prenup for protection.
The Allard decision rests on a distinction between contract rights and court powers. The court reasoned that these two invasion statutes empower the judge rather than create individual rights, so there is no individual right for the parties to waive by contract. The court declared that any agreement attempting to bind the court's equitable authority is void as against statute and public policy. Two statutory triggers allow invasion of separate property: Mich. Comp. Laws § 552.23 permits invasion when the marital estate is insufficient for a spouse's suitable support, and Mich. Comp. Laws § 552.401 permits invasion when the other spouse contributed to the acquisition or growth of the separate asset. For a business owner, the contribution statute is the larger threat: if your spouse worked in the company, managed the household to free your time, or contributed marital funds, a judge may award them a share of the business despite the prenup. Importantly, Allard did not abolish prenups. Courts still use them to identify separate property and will not invade if the agreed division is already equitable. A protect-business prenup remains valuable, but it must be paired with disciplined conduct during the marriage.
How Michigan Courts Value a Business in Divorce
Michigan courts value a closely held business at fair market value using a professional business valuation, then determine what portion is marital versus separate. A business started before marriage and named as separate property in a valid prenup begins as separate, but appreciation during the marriage may be reclassified. Valuation often requires a forensic accountant or certified business appraiser, especially for LLCs and S-corporations.
The valuation drives everything because the size of the marital estate depends on how the company is appraised. Three primary approaches exist: the income approach (capitalizing earnings or discounted cash flow), the market approach (comparing sales of similar businesses), and the asset approach (net asset value). For a service-based LLC, the income approach typically governs and raises difficult questions about personal goodwill versus enterprise goodwill. A business valuation prenup clause can lock in a valuation method and a baseline value as of the wedding date, which limits later disputes about how much the company grew. Once value is established, the court considers buyout options: one spouse buys out the other's marital share, the business is sold and proceeds divided, or rarely the spouses continue co-ownership. For an entrepreneurial prenup to function, the agreement should require both a pre-marriage valuation and a method for measuring growth, so the marital portion can be calculated cleanly rather than litigated.
Active vs. Passive Appreciation: The Core Risk to Your Business
In Michigan, passive appreciation of a separate business remains separate property, but active appreciation driven by either spouse's effort during the marriage becomes marital property subject to division. This distinction, established in Reeves v. Reeves (1997) and Hanaway v. Hanaway, is the single greatest threat to a business owner's separate-property claim, even with a prenup in place.
The rule turns on the source of the growth. Passive appreciation, such as market-driven increases in a stock portfolio or interest on a separate account, stays separate. Active appreciation, meaning growth attributable to labor, management, or reinvested marital funds, is marital. In Hanaway v. Hanaway, a husband's inherited stock was separate, but the appreciation produced by his efforts, made possible by his wife's homemaker contributions, became part of the marital estate. The owner's own effort can trigger marital treatment under Henderson v. Henderson, even without the non-owning spouse's direct involvement, though a de minimis level of effort does not convert appreciation to marital. For an LLC prenup to hold up, the agreement should expressly address business appreciation, fix a baseline value, and ideally provide the owner-spouse a fair market salary during the marriage so that personal effort is compensated rather than reinvested as marital labor. Without this language, years of hard work can quietly transfer a large slice of the company to the marital estate.
How to Protect a Business With a Michigan Prenup
To protect a business with a prenup in Michigan, the agreement must identify the company precisely, attach a current valuation, waive the spouse's interest in future appreciation, and define how any active growth is treated. Combined with disciplined financial conduct during the marriage, these steps maximize the chance a court treats the business as fully separate under Mich. Comp. Laws § 557.28.
Several drafting and behavioral practices reduce risk for business owners:
- Identify the entity by legal name, EIN, and ownership percentage, and attach a dated valuation as an exhibit.
- State clearly that the business and all appreciation, distributions, and reinvested earnings remain separate property.
- Pay the owner-spouse a market-rate salary so marital effort is compensated and not folded into the company.
- Keep business and personal finances strictly separate; never deposit distributions into joint accounts.
- Avoid titling business assets jointly or adding the spouse to the company, which can transmute the asset to marital property.
- Maintain complete documentation, because the burden of proving separate character falls on the owner.
The Wolcott v. Wolcott case illustrates success: a wife kept gifted corporate stock separate by depositing distributions only into an account in her sole name, and after 16 years of marriage the court confirmed both the stock and account were her separate property. Discipline, not just paperwork, preserves the protection.
Commingling: How Business Owners Accidentally Lose Protection
Commingling occurs when separate business property is mixed with marital property so thoroughly that it can no longer be traced to its separate source, converting the asset to marital property subject to division. For business owners, the most common mistakes are depositing company distributions into joint accounts and using marital funds to operate or expand the business, both of which can erase prenup protection.
Michigan recognizes two related dangers: commingling and transmutation. Commingled separate property becomes marital when it is no longer readily traceable to a separate source, such as routing LLC profits through a shared checking account used for household expenses. Transmutation occurs when conduct shows intent to treat a separate asset as marital, with the classic example being retitling a separately owned asset into both spouses' names. A small amount of commingling is not necessarily fatal if the owner can trace the funds back to their separate origin and show an intent to keep them separate. The protection depends on documentation: separate-property claims often fail not because the law is unfavorable but because the evidence is incomplete. For an entrepreneurial prenup to survive, the owner must maintain clean records, separate accounts, and a clear paper trail proving the business and its earnings never merged with the marital estate.
Postnuptial Agreements for Business Owners in Michigan
Michigan recognizes postnuptial agreements under Hodge v. Parks, 303 Mich App 552 (2014), but only when the agreement is intended to preserve the marriage rather than facilitate divorce. Because spouses owe each other fiduciary duties after marriage, postnups face heightened scrutiny and require additional consideration beyond the marriage itself, making them a useful but more fragile tool for business owners who marry without a prenup.
The enforceability test is stricter than for prenups. In Hodge v. Parks, the court held that a postnuptial agreement is enforceable if it seeks to keep the couple together and is equitable to both parties. By contrast, in Wright v. Wright the court invalidated a postnup designed to leave one spouse in a far more favorable position upon divorce, because it incentivized separation. A valid Michigan postnup must be written, signed, supported by full financial disclosure, voluntary, and fair at both signing and enforcement. Critically, each spouse must receive something of value they would not otherwise be entitled to under Michigan law, since the marriage cannot serve as consideration after the wedding. The arbitration statute, Mich. Comp. Laws § 600.5071, lists prenup and postnup enforceability among arbitrable matters. For a business owner who started a company after marrying, a carefully drafted postnup with independent counsel for each spouse can document the business as separate, but it will not override the court's Allard-based equitable powers any more than a prenup does.
Filing Costs and Process if Divorce Becomes Necessary
If a Michigan divorce proceeds, the filing fee is $175 without minor children or $255 with minor children under Mich. Comp. Laws § 600.2529, plus a mandatory waiting period of 60 days (no children) or 180 days (with children). Business owners should budget separately for valuation experts, which often add several thousand dollars to the total cost of a contested case.
The process begins in the Family Division of the circuit court in the county where the residency requirement is met: 180 days in Michigan and 10 days in the filing county under Mich. Comp. Laws § 552.9. Beyond the base filing fee, additional statutory costs include roughly $20 per motion, $25 to $75 for service of process, an $80 judgment fee, and a $25 e-filing system fee. Cases with minor children typically add an $80 custody and parenting-time fee. Fee waivers are available under MCR 2.002 using form MC 20 for parties who receive means-tested public assistance or whose household income is at or below 125 percent of the federal poverty guidelines, approximately $19,506 for a single person in 2026. For a business owner, the largest expense is usually the forensic valuation, not the court fees, because disputed business value drives litigation. A valid prenup that fixes valuation methods and separates the business reduces both conflict and cost. As of June 2026, verify all amounts with your local circuit court clerk.