StateTally

Missouri Alimony Calculator (2026)

RSMo §452.335 makes clear Missouri has no statutory alimony formula; courts must find the requesting spouse lacks sufficient property and cannot be self‑supporting, and any maintenance order is modifiable unless the judgment says otherwise. This tool provides a widely used American Academy of Matrimonial Lawyers rule‑of‑thumb estimate—not a legal determination.

Reviewed 2026-09-02 · Estimates only — not legal or financial advice.

Missouri has no statutory alimony formula. Courts decide case by case under RSMo § 452.335. The calculator below shows a widely used rule of thumb (the AAML guideline) as a negotiation starting point — it is not the law and a judge may land anywhere the factors justify.
Before taxes.
Before taxes.
The law behind this calculator: Missouri maintenance factors — RSMo § 452.335.

How Missouri calculates it

  • Identify the higher‑earning spouse’s annual gross income.
  • Calculate 30% of that income.
  • Identify the lower‑earning spouse’s annual gross income and calculate 20% of that income.
  • Subtract the lower‑earner’s 20% amount from the higher‑earner’s 30% amount.
  • Apply the 40% cap so the recipient’s total income does not exceed 40% of the combined income.
  • Estimate duration: 30% of marriage length if under 3 years, 50% if 3–10 years, 75% if 10–20 years, indefinite if over 20 years.

Worked example

In the example, the higher earner makes $100,000 per year and the lower earner makes $40,000 per year in a 12‑year marriage. 30% of $100,000 is $30,000; 20% of $40,000 is $8,000; the difference is $22,000 per year, which the 40% cap reduces to $16,000 per year, or about $1,333 per month as a rule‑of‑thumb starting point. For a 12‑year marriage, the duration guide falls in the 10–20‑year bracket, yielding 75% of 144 months, or roughly 108 months. The court is not bound by any of this.

Frequently asked questions

How does Missouri estimate alimony amounts?

Missouri courts consider the factors in RSMo §452.335, but a common estimate applies 30% of the higher earner’s gross income minus 20% of the lower earner’s gross income, then caps the recipient’s total income at 40% of the couple’s combined income.

Can a Missouri alimony order be changed later?

Yes. Under Missouri law, maintenance orders are modifiable unless the judgment expressly states they are permanent.

Is alimony taxable in Missouri?

Missouri follows federal treatment: alimony received is taxable to the recipient and deductible by the payor for agreements executed before 2019; post‑2019 agreements are not deductible or taxable.

How long does alimony typically last in Missouri?

Duration is guided by marriage length: 30% of the marriage term for marriages under 3 years, 50% for 3–10 years, 75% for 10–20 years, and indefinite for marriages longer than 20 years, though the court has discretion.

What recent changes affect Missouri alimony calculations?

While Missouri has not adopted a statutory formula, courts increasingly reference the American Academy of Matrimonial Lawyers guideline (30%/20% with a 40% cap) as a benchmark for reasonable support.

Is the calculation different in Kansas City, St. Louis or Springfield?

No. RSMo § 452.335 applies statewide, so courts in Kansas City, St. Louis, Springfield and every other county start from the same guideline. Local practice can differ in how judges weigh deviation factors and in typical negotiated outcomes, but the formula on this page is the one used across Missouri.

Embed this calculator

Attorneys, HR teams, and publishers: add this calculator to your own site free — copy the snippet below. Attribution stays visible.

More calculators