The published formulas are exact; the projections beyond them use your assumptions. Expand a section to see what is baked in.
β Social Security β the benefit formula
Index earnings. Each year's Social-Security-taxed earnings (capped at that year's wage base) is scaled to wage levels at the year the person turns 60 using the National Average Wage Index (AWI). Earnings from 60 on count at face value.
AIME. Sort the indexed years, keep the top 35, sum, Γ· 420 months, floor to the dollar. Years not worked are $0 and sit at the bottom.
PIA (bend points). Full benefit at FRA = 90% of the first AIME slice + 32% of the middle + 15% of the top. The bend points are set the year the person turns 62, from the AWI two years earlier (the 2026 bend points, $1,286 / $7,749, are reproduced exactly).
Claiming age. Before FRA: β5/9 of 1% per month for the first 36 months, β5/12 of 1% beyond (β70% at 62). After FRA: +2/3 of 1% per month, +8%/yr, to 70 (β124%). FRA comes from the birth year (67 for 1960+). COLAs apply every year from 62.
Statement estimate. Without an earnings record the tool anchors on the FRA amount from an SSA statement (today's dollars) and applies the same claim-age factors.
Survivor benefit. Built from the deceased's PIA, not the check they happened to be drawing: dying before claiming forfeits nothing, delayed-retirement credits earned up to death carry to a widow(er), and a deceased who claimed early leaves the greater of what they drew or 82.5% of PIA (the widow's limit). Nothing is payable before the survivor is 60; 71.5% at 60 rising to 100% at the survivor's FRA. The survivor keeps the larger of their own benefit or the survivor benefit β never both.
Children. 50% of a parent's PIA while that parent is alive and claiming, 75% once they have died, to 18 β or for life if the child's disability began before 22. A caregiver benefit (75%) is available at any age while a child under 16 or a disabled adult child is in the survivor's care. Everything on one record is capped by the family maximum (150β188% of PIA by the 2026 bend points); the worker's own benefit is never cut, dependants share what is left, and a widow's delayed credits sit outside the cap. Children's benefits are the child's income and stay out of the parents' taxable income.
Trust-fund stress test. Off by default (current law schedules full benefits). When ticked, every Social Security stream is paid at 78% from late 2032 (OASI) or 83% from 2034 (OASDI), per the 2026 Trustees Report; the depletion year is a blend of full and reduced months.
β‘ Savings β contributions, growth & drawdown
Contributions. Contribution % Γ salary, capped at the IRS elective-deferral limit: 2026 = $24,500 base, +$8,000 catch-up at 50+, +$11,250 super catch-up at 60β63, indexed with your inflation assumption; the employer's share sits outside the limit. They stop when that person stops working, prorated in the final year. The balance-as-of date makes the first year a partial year: balances grow only for the rest of it and only that fraction of the year's contributions still arrives. Contributions earn half a year's growth.
Two drawdown models. A set percentage: the first withdrawal is your rate Γ the balance in the first withdrawal year, then that dollar amount rises with inflation while the balance keeps earning (the "4% rule" as commonly modelled). Only what the bills need: each year draws just enough β after every other income stream and the tax on the draw itself β to cover bills and health costs plus your cushion, taking the already-taxed side account first. RMDs are a floor for both.
Penalty-free money first. A traditional draw is allocated across the two people so that whoever's pre-tax money is already penalty-free (59Β½, the Rule of 55 / 50 for public safety, or a 72(t) plan) is drawn before anyone pays a 10% penalty; within the same status the split is by balance. Roth is split by balance.
Surplus. Once fully retired, income above bills is banked in an after-tax side account (taxed on its gains) rather than vanishing.
RMDs. Forced from 73 using the IRS Uniform Lifetime Table, from traditional balances; if the RMD exceeds the planned draw the larger amount is withdrawn and taxed.
Roth conversions. Fill to the top of a chosen bracket (solved against the real taxable income, including how much of Social Security becomes taxable) or a fixed amount, between two ages. The year's draw comes out first and the conversion moves what is left. The impact panel re-runs the whole plan without the ladder and nets income tax saved against any IRMAA it triggers; break-even projects both to 115.
β’ Pensions β FERS and private
FERS basic annuity = high-3 Γ creditable service Γ 1.0% (or 1.1% at 62+ with 20+ years; unused sick leave counts toward that 20-year test). Special-provisions employees earn 1.7% for the first 20 years. High-3 is modelled as the last three projected salary years. Creditable service runs from the Service Computation Date to the last day worked, plus sick leave at 2,087 hours = 1 year (it counts toward the computation, not eligibility).
Eligibility. Immediate and unreduced at 62+/5, 60+/20 or MRA+30; MRA+10 is reduced 5% per year under 62; below that it is deferred (no sick-leave credit, no FEHB continuation, no supplement).
FERS COLA is the "diet" COLA and starts at 62: inflation β€2% in full, 2β3% capped at 2%, above 3% inflation minus 1. Special-provisions retirees get COLAs from retirement.
Special Retirement Supplement. Immediate, unreduced retirement before 62 adds β (SS at 62) Γ (FERS years Γ· 40) until 62.
Survivor election. 50% (annuity β10%), 25% (β5%) or none. The survivor receives that share for life.
Death in service. A FERS employee who dies before retiring with 10+ years leaves 50% of the annuity earned so far (1% Γ years Γ pay), plus the Basic Employee Death Benefit ($41,714 in 2026, indexed) and half of final pay as a lump.
Private pensions are entered as a monthly amount in today's dollars with their own COLA rule (none, fixed, or full inflation) and survivor share.
Military retired pay is taxable ordinary income, COLA'd, for life; VA disability is tax-free and excluded from every tax base. Each stops at that person's death (SBP/DIC not modelled).
β£ Taxes
A federal estimate on 2026 brackets and the standard deduction (with the 65+ addition per person actually 65+), indexed forward by your inflation assumption. Married filing jointly while both are alive, single for the survivor β the "survivor tax torpedo" is modelled, not assumed away.
Taxable: wages, pensions, the supplement, military pay, traditional withdrawals and conversions. Up to 85% of Social Security via the provisional-income formula, whose thresholds are frozen in law. Roth withdrawals, VA pay and children's benefits are not taxed here.
State tax is a flat top rate on ordinary income (Social Security included only where the state taxes it), chosen from the "retire in" state.
Medicare IRMAA (65+, per person) is set by the MAGI from two years earlier and counted as a bill with the Part B premium and health plan, not netted out of income. The conversion's own tax is reported separately in the ladder panel as the cash it needs.
β€ Bills, health, and the timeline
Bill lines are today's $/month with a start and end age (Person A's), a one-time option (the total lands in a single year), a Disc flag, and their own growth rate (blank = inflation, 0 = fixed dollars, n = n%/yr). The go-go / slow-go / no-go curve bends only Disc lines. Bills start when the first person retires, prorated in that year, and drop to the survivor share once someone has died.
Health. A per-person premium before 65 and a per-person Medicare supplement from 65, plus one household plan for life (FEHB for feds β forfeited by a deferred FERS retirement), the Part B base premium from each person's 65 (full year), and IRMAA. All inflate with your assumption.
Calendar accuracy. Retirement and claiming are placed on the real calendar by birth month and day: the retirement year has a partial year of salary (down to the day for a mid-month exit), the pension starts the month after separation, Social Security the month it is claimed. Ages in the table are the age reached that year.
Dollars. "Today's dollars" deflates every year back to now by your inflation assumption; "future dollars" shows the actual nominal amounts. Life-insurance face values are never inflated.
β₯ What this does NOT model
β’ Sequence-of-returns risk β growth is a smooth average, not real volatility.
β’ The SS earnings test (claiming before FRA while still working) and WEP/GPO.
β’ ACA subsidies before 65; precise state brackets and exclusions; local taxes; the temporary 2025β28 senior bonus deduction.
β’ HSA drawdown, SBP/DIC, the 27-pay-period year, the 18-month BEDB service requirement, SSI interactions for a disabled adult child (the DAC calculator covers that in depth).
Treat every number as a planning estimate. Authoritative figures live at ssa.gov, OPM and tsp.gov.
β¦ Key numbers baked in (2026)
Social Security: AWI through 2024 = $69,847 Β· wage base 2026 = $184,500 Β· bend points $1,286 / $7,749 Β· family-maximum bend points $1,643 / $2,371 / $3,093 at 150/272/134/175%.
IRS: elective deferral $24,500 Β· catch-up 50+ $8,000 Β· super catch-up 60β63 $11,250 Β· a governmental 457(b) has its own equal limit Β· IRA $7,500 (+$1,100 at 50+) Β· RMDs from 73 (Uniform Lifetime Table).
FERS: 1.0% / 1.1% (special provisions 1.7% first 20 yrs) Β· sick leave 2,087 hrs = 1 yr Β· MRA 57 (1970+) Β· diet COLA from 62 Β· BEDB $41,714.
Tax & Medicare: standard deduction $32,200 MFJ / $16,100 single, +$1,650 / $2,050 at 65 Β· SS up to 85% taxable, thresholds frozen Β· Part B $202.90/mo Β· IRMAA tiers from $218k MFJ / $109k single.
β§ Glossary
AIME, Average Indexed Monthly Earnings. Β· PIA, Primary Insurance Amount β the full benefit at FRA. Β· FRA, Full Retirement Age (67 if born 1960+). Β· AWI, Average Wage Index. Β· COLA, the annual inflation adjustment. Β· DRC, delayed-retirement credits for claiming after FRA. Β· DAC, disabled adult child β a child whose disability began before 22.
RMD, Required Minimum Distribution. Β· Rule of 55, separate at 55+ and workplace-plan withdrawals are penalty-free before 59Β½ (50 for public safety). Β· 72(t), substantially equal periodic payments, penalty-free at any age. Β· IRMAA, the income-based Medicare premium surcharge. Β· MAGI, modified adjusted gross income.
FERS, the federal pension. Β· SCD, Service Computation Date. Β· High-3, the highest three consecutive salary years. Β· MRA, Minimum Retirement Age. Β· SRS, Special Retirement Supplement. Β· FEHB, federal health insurance. Β· FEGLI, federal group life insurance. Β· BEDB, Basic Employee Death Benefit. Β· TSP, Thrift Savings Plan β the federal 401(k).