Yet Another Personal Finance Tool · MFJ · TY2026 (OBBBA) · Taxes + cash flow + retirement + net worth + estate · two-state comparison · Monte Carlo
Doc No.YAPFT-001
RevB
Filing StatusMFJ
Std Deduction$32,200
SALT Cap$40,400
Sheet1 of 1
Legacy wealth (today's $, plan as set)
This year
Flags
§1 Inputs
Grouped like a traveler on a routing sheet: each person's own operations first, then the children's, then the fixture (house), then everything shared. Every control drives the full lifecycle model.
Person 1 — LLC owner
Person 2
Children
House & mortgage
Cars — two loans
Household & plan — shared
§2 Verdict — total annual burden
Federal income tax (best of standard vs. itemized) + self-employment tax + state income tax + property tax, at the snapshot year selected above. Mortgage principal isn't a tax; it's excluded.
State A
State B
Delta (A − B)
§2B Filing day — refund or bill
Withholding is escrow, not the bill. Your liability is the bill; withholding is the deposit you've been prepaying all year. A refund means you overpaid the deposit (an interest-free loan to the IRS), a balance due means you underpaid — either way the bill itself didn't change. Auto mode estimates withholding via the W-4 percentage method for a single MFJ job; two-earner households systematically under-withhold on default W-4s, so uncheck auto and plug in real paystub numbers when you have them.
State A — filing estimate
State B — filing estimate
§2B2 Lifetime refund / owed
The snapshot above, extended down the whole timeline using a lifetime withholding model: W-4 percentage method on wages, the default 10% on 401k distributions, and nothing on Roth conversions — which is exactly how real people get surprised. Withholding is deposit tolerance; conversions blow right past it. Positive = refund (an interest-free loan you made), negative = owed at filing.
§2C Monthly cash flow
Gross to net to what's left after the house, at the snapshot year selected in §1. 401k deferrals come off the top pre-tax (income tax only — FICA still takes its cut). 529 contributions come out post-tax. Mortgage P&I (including your extra payments) and property tax then come off net pay. P&I drops to zero once the loan pays off — drag the snapshot year past payoff to see the cliff.
State A — monthly
State B — monthly
§2D Monthly budget — where the discretionary goes
Percentages apply to the discretionary figure from §2C (net pay after every account contribution, minus housing). Think of them as scrap rates on your take-home throughput: whatever survives the four categories becomes work-in-progress inventory — a savings account that compounds (return shown, minus a 15% tax-drag haircut) and feeds the §10 net worth stack as its own band.
State A — budget
State B — budget
§3 Itemized vs. standard — the crossover
Mortgage interest front-loads: year 1 is the peak, then it decays every year while the standard deduction is flat (and inflation-indexed upward — held constant here). At some loan year your itemized total drops below $32,200 and standard wins. Extra payments accelerate that crossover — you save real interest but retire the deduction sooner.
§4 House price sweet spot
Federal tax saved by itemizing instead of taking standard, as a function of purchase price (year-1 snapshot, current rate/term/down). The knee of each curve is the price where itemizing starts beating standard — below it, your mortgage interest and property tax are partially “wasted” inside the standard deduction. Above it, each marginal $1 of interest/property tax only returns ~$0.22–0.24 federal. There's no price that “maximizes returns” in absolute terms — bigger deductions always cost more than they save — but there is a threshold below which the deduction machinery does nothing for you.
§5 Rate × term matrix (X = 5.95–6.50, Y = 15/20/30 + extra payments)
Total interest paid over the life of the loan, in $k, at the current price and down payment. Second line: payoff time / year-1 interest deduction. Click a cell to load it into the worksheet.
§6 LLC grid + S-corp check
Profit modeled as margin-on-revenue: profit = opex × m / (1 − m). Pass-through profit picks up SE tax (15.3% on 92.35%), a 20% QBI deduction federally, and MA's 5% (NH has no personal income tax; NH BPT only kicks in above ~$109k gross receipts — not in play until revenue is well past this grid). Modeled as an in-state LLC with each state's annual report fee baked in (MA $500 / NH $100 / VT $35 / ME $85). The Yes/No LLC toggle in §1 zeroes the whole module — profit, SE tax, QBI, and fees.
§7 Charitable giving — does it move the needle?
2026 rules: non-itemizers get up to $2,000 (MFJ) above the standard deduction; itemizers face a new 0.5%-of-AGI floor (first ~$1,000 of giving at this income deducts nothing). MA separately allows a charitable deduction against its 5% tax regardless of federal itemizing. The chart shows total burden vs. giving level; the readout shows your true after-tax cost per dollar donated at the current setting.
§8 Retirement engine — 401k × 2 + Roth IRAs + 529
Each earner gets a 401k with its own balance and return; contributions flow in from the §1 deferral slider while that earner works. IRAs are modeled as Roth — at this income with a workplace plan, a traditional IRA is nondeductible anyway, so it's tax-the-seed vs tax-the-harvest, and Roth (front door or back) is the sane default. Each IRA has its own balance, return, and contribution, on its owner's age clock. Withdrawals are a fixed % skim off a tank that's still being heated: the level and the skim move together, so it never runs dry, but a lean year shrinks both. Custodial (UTMA) accounts are the anti-529: taxable growth via the kiddie tax (modeled — first $1,350 of each kid's annual gains free, next $1,350 at 10%, the rest at your marginal rate, paid from the account) but no spending restrictions — and they're the child's property from the first deposit; you're just the machinist of record until 18, when the keys transfer and it leaves household net worth. Children run as staggered production lines: same process plan (CTC to 16, contributions to 17, college 18–21), offset start dates via the child-2 slider. "Today's $" deflates by the §1 inflation slider — future dollars are catalog prices from a 2055 catalog; today's-dollar view re-quotes everything in the current one.
Accounts at owner's retirement
Combined pot & withdrawals
529 — per child at 18
§9 Lifetime monthly cash flow — working years into retirement
Net after-tax take-home minus mortgage P&I and property tax, stacked: employment income in steel, retirement income in gold. Housing is charged against employment income first, overflow against retirement income. Watch three events: the mortgage payoff cliff (P&I vanishes), each earner's retirement (steel shrinks, gold appears), and the 529 contribution years ending. Everything recalculates from every other control on this page.
§9B Where every dollar goes
Gross monthly income stacked into its destinations, year by year: taxes, retirement contributions, kids, housing, cars, living, other (charity/ACA/fees), and surplus on top. Watch stations close — each car loan ending, the mortgage payoff, 529 contributions stopping — and their takt time get reabsorbed into the surplus band. Follows the §9 state selector.
§10 Net worth through retirement
Home equity + both 401ks + Roth IRAs + 529s + custodial, stacked through the end of retirement, with the dashed line reading the right axis: the house's share of total net worth. Retirement/529/custodial balances are state-agnostic, but the savings band is built from each state's budget surplus — so this chart follows the §9 state selector. Appreciation compounds the assessed value, which also raises property tax every year in §2/§9 — the house gets more valuable and more expensive to hold simultaneously. The 529 band ramps to 18, drains through the college years, and any residual keeps compounding (up to $35k can roll to the kid's Roth IRA).
§11 Trusts & the estate layer
Three trust flavors, honestly priced. A revocable living trust is a fixture plate for your assets — everything mounted and labeled so the handoff (death, incapacity) skips the probate re-fixturing — but the IRS sees straight through it: zero tax delta, its value is administrative. A credit-shelter (bypass) trust attacks the real tax at this wealth level: state estate tax. Each spouse gets a duty-free allowance (MA: $2M, use-it-or-lose-it, not transferable); leaving everything outright to the survivor wastes station 1's allowance — the bypass trust banks it, doubling the shelter. And a standing warning on non-grantor irrevocable trusts for income: trust brackets are compressed — 37% federal at roughly $16k of retained income — a machine that redlines in first gear; income-shifting into one almost always raises tax at this level.
State A — estate at end of plan
State B — estate at end of plan
§12 Optimizer — retained-wealth DOE
A design-of-experiments sweep over the levers that change tax efficiency without changing your lifestyle: which state you live in, Roth conversion sizing, mortgage term and extra payments, and the credit-shelter election. Income, spending percentages, deferral, and withdrawal rate stay fixed — same parts, different process routing. Objective: end-of-plan net worth in today's dollars, minus state estate tax (legacy wealth). Click a row to load it into the worksheet.
Not run yet.
§14 Offshore — the honest aisle
§13 Risk — Monte Carlo & sensitivity
Flat returns are the nominal drawing; Monte Carlo is the tolerance stackup — 250 builds of the same plan with real market variation (one correlated draw per year across every account), then read the process capability: what fraction of builds stays in spec. The tornado is the other instrument: perturb each lever one at a time, rank by how hard it swings legacy wealth — it tells you which sliders deserve your attention.
Not run yet.
Not run yet.
FEDERAL TY2026 (OBBBA): MFJ std deduction $32,200 (indexed) · brackets indexed · SALT cap per current law: $40,400 +1%/yr through 2029, unindexed $10,000 from 2030 · mortgage interest + PMI deductible on ≤$750k acquisition debt (prorated) · PMI auto 0.6% of balance while LTV > 80%, appreciation counts toward escape · CTC $2,200/child (indexed), −$50 per $1k MAGI over $400k (unindexed, as in law) · addl Medicare 0.9% over $250k (unindexed) · SE tax 12.4% to wage base + 2.9%; LLC owned by Person 1 · QBI 20%, thresholds indexed, no-W-2 phase-out $403.5k–$553.5k · charitable: 0.5% AGI floor itemizing, $2k above-the-line otherwise · 401k $24,500/person + employer match (total-limit interaction ignored) · IRA $7,500/person as Roth (traditional nondeductible here; assume backdoor if over MAGI limits) · RMDs at 75 (SECURE 2.0), Uniform Lifetime Table, per traditional 401k, max(skim, RMD); Roth exempt; current-year balance approximation · Roth conversions: retirement→75 window, proportional, ordinary income · Social Security 85% federally taxable, COLA = inflation · kiddie tax $1,350 / $1,350 @10% / rest @ parents' marginal (indexed, realized annually, paid from account; LTCG rates simplified to ordinary).
STATE: MA 5.0% flat + Fair Share 4% over $1,107,750 (indexed); $8,800 exemption + FICA-paid deduction ($4k cap); taxes 401k/IRA distributions and conversions; SS exempt; 529 deduction ≤$2,000/return · NH: no wage tax, I&D repealed 2025 · VT (2025 figs, indexed): 3.35–8.75% MFJ brackets, $14,850 std + $5,100/person exemption, SS taxed above $75k AGI (phased from $65k), 3%-of-AGI minimum over $150k, 5% charitable credit (first $20k), 10% VHEIP 529 credit (first $2,500/kid) · ME (2025 figs, indexed): 5.8/6.75/7.15% MFJ brackets, federal-matching std deduction + $5,150/person exemption, SS fully exempt, pension deduction $48,216/person on 401k/IRA distributions (phaseout >$250k AGI modeled linearly to $350k) · LLC annual report MA $500 / NH $100 / VT $35 / ME $85 · State withholding auto-estimate applies to State A only.
LIFECYCLE: child 1 born year 1, child 2 offset per Children section; CTC to 16, 529/custodial contributions to 17, 529 spent 18–21, custodial exits household NW at 18 · withdrawals = % of remaining balance per retired account · home appreciation drives equity and property tax.
ESTATE/TRUST: federal exemption $15M/person (not binding); state exemptions MA $2M / VT $5M / ME $7M (ME indexed), non-portable; schedules approximated; credit shelter modeled as 2× exemption at second death; revocable trust = grantor trust, no tax effect; non-grantor trust income brackets compressed (37% ≈ $16k) — shown as warning, not modeled as a strategy. BUDGET/CASH: category %s apply to discretionary; charity now subtracted from cash flow (fixed); surplus compounds at savings return with 15% drag EXCEPT years under the 0% LTCG ceiling (~$98.9k MFJ taxable, indexed — tax-gain harvesting) · HSA: $8,750 family limit (indexed), above-the-line fed+state, tax-free skim in retirement (assumed medical; FICA exemption via cafeteria plan not modeled) · ACA gap: retired pre-65, $12k/person benchmark, 2026 post-enhancement rules with the 400% FPL subsidy cliff (9.5% cap) — conversions and subsidies compete for MAGI · QCD: from age 71, charity ≤ withdrawals routed AGI-free (assumes 401k→IRA rollover; $108k/person limit not binding) · Conversions: fixed $ or fill-to-bracket-top (12/22/24), sized per year · Downsize: sale at E1 retirement, 6% costs, §121 $500k shield, 15% LTCG on excess, proceeds → savings, rent thereafter · Tuition: per kid ages 18–21, inflates CPI+2pts, 529 first then cash; at $0 the 529 simply holds · Monte Carlo: 250 runs, one correlated normal draw/yr across all returns · Inheritance: income-tax-free lump (today's $, inflated to receipt year), routed to savings or mortgage-first; stepped-up basis assumed · Cars: two amortized loans (payments end at term; freed payment reabsorbed by surplus, fully so in fixed-budget mode), values depreciate 12%/yr and sit in net worth · Budget modes: % of base (post-housing, post-car) or fixed $ inflated at CPI; negative surplus = under budget, drains savings · Lifetime withholding model: W-4 pct method on wages, 10% on 401k distributions, none on conversions — refund chart and era suggestions built from it. SURVIVOR: spousal rollover merges accounts, SS ×0.67, filing single thereafter (single brackets/std exact; state exemptions and bracket widths halved as approximation) · Catch-ups: +$8k @50, +$12k @60–63 (indexed); forced Roth above $145k wages (SECURE 2.0); Roth-split slider routes base deferral (taxed at entry, no RMD) · Guardrails: real target = rate × pool at first withdrawal; ±20% rate bands trigger ∓10% spending steps; RMD floors still enforced · LTC: final N years, CPI+2 inflation, deductible medical above 7.5% AGI · Spending smile: ×1.1 first 10 retirement yrs, ×0.9 next 10, ×0.8 after · 2nd home: bought at appreciated price, down from savings, interest deductible under the COMBINED $750k acquisition cap (balance-based approximation), property tax at State rate into SALT, equity in NW · Savings rate = (401k both types + IRA + HSA + 529 + custodial + positive surplus)/gross · Standard-of-living ratios = real living spend vs year 1 · Offshore section is educational; FEIE illustration assumes E1's wages fully qualify. NOT MODELED: HSA, AMT, NIIT, other credits, home-sale costs/§121, VT property-tax income adjustment, ME dependent credit (phased out at these incomes), MA senior circuit breaker, sequence-of-returns risk. Planning sketch, not tax advice.