Divorce Financial Calculator — Methodology

How This Calculator Works

Divorce changes retirement in three ways at once, and they are usually assessed separately by different professionals. This calculator puts them in one place.

1. The QDRO split. A Qualified Domestic Relations Order divides retirement accounts. The calculator models both defined-contribution balances (401(k), IRA) and defined-benefit pensions.
2. Divorced-spouse Social Security. If the marriage lasted ten years or more, you may claim on your ex-spouse's record. This does not reduce their benefit, and they need not consent.
3. The projection for each person afterwards. Two separate retirement paths from the post-split balances.

Inputs and Assumptions

• Marriage length: The ten-year threshold is the single most consequential input for Social Security.
• Account balances and split percentage: Applied to defined-contribution accounts.
• Pension details: Modelled separately from account balances, since pensions divide differently.
• Each spouse's age and earnings record: Used for the individual projections and benefit estimates. A Social Security estimate you enter is taken as the benefit at full retirement age; left at 0, it is estimated from income, counting each year only up to the wage base ($184,500 for 2026) and holding the result to SSA's published maximum ($4,152 for 2026).
• Social Security start: your retirement age, but never before 62 (20 CFR 404.310) or after 70, at the amount for that age. If you retire earlier, the calculator shows the years before 62 separately.
• Today's dollars: Social Security estimates and the 80% income target are in today's dollars, so balances are grown at the real return, (1 + return) / (1 + inflation) − 1, with inflation at 2.5% unless you change it, and savings held at 15% of today's income.

Formula

// Primary Insurance Amount — 2026 bend points
tier1 = min(AIME, 1286) × 0.90
tier2 = max(0, min(AIME, 7749) − 1286) × 0.32
tier3 = max(0, AIME − 7749) × 0.15
PIA   = tier1 + tier2 + tier3

// AIME from income: min(income, 184,500) / 12; PIA held to $4,152

// Social Security starts at claimAge = min(max(retirementAge, 62), 70)
own = PIA reduced 5/9% a month (first 36) and 5/12% beyond before FRA,
      or + 2/3% a month after FRA

// Divorced-spouse benefit (marriage >= 10 years): half the ex's PIA.
// Applying for one is applying for both (born 2 Jan 1954 or later),
// so SSA pays your own benefit plus a top-up, from the same month:
topUp = max(0, 0.5 × exPIA − PIA) reduced 25/36% a month (first 36)
        and 5/12% beyond; no delayed credits
total = max(own, own without delayed credits + topUp)

// QDRO split
splitAmount     = accountBalance × splitPercentage
retainedBalance = accountBalance − splitAmount

// Projection in today's dollars
realReturn = (1 + return) / (1 + inflation) − 1
balance    = share × (1 + realReturn)^years
           + 0.15 × income × ((1 + realReturn)^years − 1) / realReturn

// Post-divorce sustainable income
annualIncome = balance × 0.04   // 4% withdrawal rate
monthly      = annualIncome / 12 + pension share + total (from claimAge)
gap          = 80% × combined income / 12 / 2 − monthly

Data Sources

• Social Security Administration — Primary Insurance Amount formula, 2026 bend points ($1,286 and $7,749), and the divorced-spouse eligibility rules including the ten-year marriage requirement (20 CFR 404.331, 404.333).
• Federal Register 90 FR 49047 (November 3, 2025) — 2026 wage base, $184,500; SSA 2026 COLA fact sheet — $4,152 maximum at full retirement age.
• 20 CFR 404.310, 404.313 and 404.410 — earliest age 62, delayed credits, and reductions for age.
• Own benefit plus spousal excess — 42 U.S.C. 402(q)(3)(B) and 402(k)(3)(A); SSA POMS RS 00615.020 and RS 00615.694. Deemed filing — Bipartisan Budget Act of 2015, section 831; SSA POMS GN 00204.035.
• Employee Retirement Income Security Act (ERISA) — the statutory basis for Qualified Domestic Relations Orders.
• For official benefit projections use ssa.gov/myaccount.

Limitations

• This is not legal advice, and divorce is jurisdictional. Property division depends on your state — community property states divide differently from equitable distribution states. Use a family law attorney.
• Historical earnings are not wage-indexed, so Social Security figures are approximations.
• Uses 2026 bend points, which are adjusted annually.
• Does not model alimony or child support, or their tax treatment.
• Does not model the tax consequences of dividing accounts, including early-withdrawal penalties where a QDRO distribution is taken in cash.
• Does not model the cost basis of taxable assets, which often makes a nominally equal split unequal after tax.
• Does not model survivor benefits on a divorced record, or remarriage, which can end eligibility.
• Pension division depends on plan rules and the language of the order; a plan administrator must approve any QDRO.
• The 4% withdrawal rate is a rule of thumb, not a guarantee.
• Both spouses are taken to be the same age, and the ex-spouse to be eligible when you claim (62 or older and divorced for 2+ years).
• The pension share is taken as entered, in today's dollars.

Last Updated

July 2026 — Methodology page published (engine then used the 2024 SSA bend points).

October 2026 — Engine moved to the 2026 SSA bend points ($1,286 and $7,749), from the shared source src/lib/tax/data/social-security.ts.

October 2026 — Balances are now in today's dollars, like Social Security and the target (before, a nominal balance could show “no gap” where there is one). Social Security no longer counts before 62 or at its full-retirement-age amount at any age, earnings above the wage base no longer count, and a divorced spouse gets their own benefit plus a top-up rather than the higher of the two.