Alimony in New Hampshire: The 23% Formula, Duration Caps, and What Triggers Termination

New Hampshire overhauled its alimony laws under RSA 458:19-a to replace judicial guesswork with a specific mathematical formula and hard duration limits. If your divorce petition was filed on or after January 1, 2019, the court uses this standardized framework — not the open-ended discretion that created wildly inconsistent awards in earlier decades.

Here's exactly how the calculation works, how long it lasts, and what events end it early.

The 23% Formula

Under RSA 458:19-a, II(a), the maximum monthly alimony award is the lesser of two numbers:

1. The payee's proven reasonable monthly need
2. 23% of the difference between the parties' adjusted gross incomes

The formula: Monthly Alimony = min(Payee's Reasonable Need, 0.23 × (Payor's AGI − Payee's AGI))

"Adjusted Gross Income" is calculated by taking each spouse's gross income and making specific adjustments:

• Subtract: court-ordered and actually paid child support or alimony for prior relationships, plus the cost of health insurance premiums paid for the other party
• Add (to the payee's income): any child support ordered for the parties' joint children in the current case

The 23% rate applies under current federal tax law, where alimony is not deductible to the payor and not taxable to the payee. If Congress changes the law to make alimony deductible/taxable again, the formula automatically jumps to 30%.

A Worked Example

Spouse A earns $120,000 per year ($10,000/month). Spouse B earns $40,000 per year ($3,333/month). Spouse B's documented reasonable monthly needs total $4,500.

Step 1: Income difference = $10,000 − $3,333 = $6,667

Step 2: 23% of the difference = $6,667 × 0.23 = $1,533

Step 3: Compare to reasonable need = min($4,500, $1,533) = $1,533/month

The formula caps the award at $1,533 even though Spouse B claims $4,500 in monthly needs. The reasonable need amount only controls if it's lower than the formula result.

Duration Caps

The maximum duration of term alimony is strictly capped at 50% of the length of the marriage, measured in months from the wedding date to the date the divorce petition was served.

A 12-year marriage (144 months) means a maximum alimony term of 6 years (72 months). A 20-year marriage caps at 10 years. There's no lifetime alimony provision in New Hampshire's current statute.

Two Types of Alimony

Term alimony is the standard form — periodic payments that allow both parties to maintain a reasonable standard of living based on their marital lifestyle. This is what the 23% formula calculates.

Reimbursement alimony compensates a spouse for specific economic contributions to the payor's career or education. If you worked to put your spouse through medical school, reimbursement alimony addresses that investment. This form is less common and calculated based on actual contributions rather than the income formula.

What Ends Alimony Early

New Hampshire law establishes several automatic termination triggers:

Retirement. Term alimony ends when the payor reaches full Social Security retirement age or actually retires, whichever is later — unless the parties explicitly agreed otherwise in writing.

Cohabitation. Alimony must terminate or be reduced if the payor proves the payee is cohabiting with another unrelated adult in a relationship "resembling that of a marriage." The court looks at three factors: continuous cohabitation in a primary residence, sharing of household expenses, and economic interdependence.

Remarriage. Alimony ends automatically when the payee remarries.

Death. Alimony terminates upon the death of either party.

Modifying an Existing Order

Changing an alimony order after it's been entered is intentionally difficult. Under RSA 458:19-aa, the requesting party must prove by "clear and convincing evidence" — a higher standard than the usual "preponderance" — that:

1. There's been a substantial, unforeseeable change in circumstances
2. The modification won't cause undue hardship
3. Justice requires the change

Job loss, significant health changes, or the payor's involuntary retirement can qualify. A voluntary reduction in income to reduce alimony payments will not.

Documenting Your Position

Whether you're expecting to pay or receive alimony, the calculation depends entirely on two things: accurate income figures and documented reasonable needs. The Financial Affidavit (Form NHJB-2065-F) is where both parties present their monthly income and expenses to the court.

The New Hampshire Divorce Financial Split & Asset Division Guide includes an Alimony Estimator worksheet that runs the 23% formula with your actual numbers, plus a monthly budget planner to document reasonable needs for the court affidavit.

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