How Alimony Is Calculated
Alimony — also called spousal support or maintenance — is the most unpredictable number in a divorce. Two couples with nearly identical finances can get very different awards depending on the state, the judge, and the story behind the marriage. That's because, unlike child support, most states have no fixed formula for alimony. Here's what actually drives it.
Why there's no national formula
Child support is formula-driven in every state because the goal is narrow and measurable: cover a child's costs. Alimony is fuzzier — its purpose is to limit the unfair economic damage a divorce does to a lower-earning spouse, and "unfair" depends on context. So most states hand judges a list of factors to weigh rather than an equation to solve. A minority of states and counties publish guideline formulas, but even those are often advisory starting points a judge can depart from.
The factors judges weigh
While the exact list varies, courts across the country consider some combination of:
- The income gap between the spouses, and each one's earning capacity
- Length of the marriage — longer marriages support longer or larger awards
- Standard of living established during the marriage
- Age and health of each spouse
- Contributions to the marriage, including a spouse who left the workforce to raise children or support the other's career
- Time and training needed for the lower earner to become self-supporting
- Each spouse's assets after property division
- In some states, marital fault such as adultery
The common guideline calculations
Where guidelines exist, two patterns show up repeatedly. Our alimony estimator offers both:
- The income-difference method. A frequently cited version takes roughly 30% of the higher earner's income minus 20% of the lower earner's. The bigger the gap, the bigger the support.
- The income-share method. Support equals a percentage (often around 40%) of the difference between the two incomes.
Both are typically capped so the recipient doesn't end up with more income than the payer — a common guardrail is that support can't lift the recipient above roughly 40–50% of the couple's combined income. Treat any formula result as a midpoint with a range around it, not a precise figure.
How long alimony lasts
Duration usually scales with the length of the marriage. A widespread rule of thumb is support for somewhere between a third and a half of the years married. Many states also recognize categories:
- Temporary support during the divorce process
- Rehabilitative support for a set period while the recipient gets education or training to become self-supporting
- Long-term or permanent support, most common after long marriages (often 20+ years) or where a spouse can't realistically become self-supporting due to age or health
Support typically ends if the recipient remarries, and often if they cohabit with a new partner, or if either spouse dies.
The 2019 tax change everyone gets wrong
For divorces finalized before 2019, alimony was tax-deductible to the payer and taxable income to the recipient. For divorces finalized in 2019 or later, U.S. federal law flipped this: alimony is no longer deductible for the payer and no longer taxable to the recipient. This matters in negotiation — the after-tax cost and value of support changed meaningfully. Some states treat alimony differently on state taxes, so check with a CPA.
How to use the estimate
Because alimony is discretionary, the smartest move is to walk in with a realistic range rather than a single hoped-for number. Use the alimony estimator to generate that range from the two incomes and the marriage length, then pressure-test it against the factors above and your state's rules with a family-law attorney. Pair it with the asset division calculator to see the full settlement picture — sometimes a larger share of assets is traded for lower support, or vice versa.
General education, not legal or tax advice. Alimony rules vary widely by state and the award is ultimately a judge's decision. Confirm with a licensed attorney.