Household Finance DemoDWhat-if math computed from the synthetic budget, accounts, and tax anchors. Every assumption is printed on this page; changing the generator inputs changes the next deterministic build. As of 2026-10-22.
Assumptions: mortgage 6.50% 30-year fixed (fictional fixed rate); second rate scenario 7.25%. Property tax 1.8% of price per year, insurance 0.5%, HOA $0.00/mo, closing costs 3.0%; PMI at 0.7% of the loan per year whenever the down payment is under 20%. Gross income $248,400.00 today.
How the savings pace is built: from the synthetic budget itself — income grows at 3.0%/yr, spending at 2.5%/yr, so monthly saving widens from $2,200.00 to $2,600.00. Childcare is in the budget at its fictional full-cost level through 2029-08, then drops to $600.00/mo of aftercare. The fund is invested at a 5.0% long-run return estimate; gains are taxed at an estimated 15.0% when sold, and the prices below use the after-tax usable fund.
Starting fund: synthetic bank accounts $31,500.00 + demo money-market reserve $0.00 = $31,500.00 — all of it sits under the $24,000.00 emergency fence, so excess liquid is $7,500.00. The fictional down-payment portfolio ($12,000.00) is counted only in the scenario that includes it.
| Usable fund (with DP portfolio) | Usable fund (without) | Healthy price · 20% down | Healthy price · 10% down | |
|---|---|---|---|---|
| Year 1 (2027) | $41,500.00 | $29,500.00 | $207,500.00 | $174,300.00 |
| Year 2 (2028) | $51,000.00 | $39,000.00 | $255,000.00 | $214,200.00 |
| Year 3 (2029) | $60,500.00 | $48,500.00 | $302,500.00 | $254,100.00 |
| Year 4 (2030) | $70,000.00 | $58,000.00 | $350,000.00 | $294,000.00 |
| Year 5 (2031) | $79,500.00 | $67,500.00 | $397,500.00 | $333,900.00 |
Year-5 grid at 6.50% (with the DP portfolio / without it, nominal · today's dollars): 20% down $397,500.00 · $381,600.00 / $318,000.00 · $302,100.00; 10% down $333,900.00 · $381,600.00 / $318,000.00 · $302,100.00. At 20% down the cash still binds; at 10% down the payment rule (PMI included) binds instead. Today's-dollars figures deflate at 3.0%/yr of assumed home-price inflation.
Synthetic scenario inputs for the demo.
| Monthly change | Amount |
|---|---|
| Childcare (Little Oak, sibling discount) | +$700.00 |
| Health insurance (family plan increase) | +$180.00 |
| Groceries & household | +$150.00 |
| Healthcare | +$75.00 |
| DCFSA extra pre-tax saving | −$200.00 |
| Total | +$905.00/mo |
While both childcare bills overlap, the monthly contribution runs negative (about +$1,900.00 in year 2 (2028), +$1,800.00 in year 3 (2029)); the fictional childcare step-down brings it back to roughly break-even, then positive. A one-time $3,500.00 arrival cost lands in the arrival year. Under the synthetic baseline, the fund absorbs the deficit years instead of emptying — it bottoms at $37,000.00 in year 1 (2027).
| Monthly contribution | House fund — with child | House fund — baseline | |
|---|---|---|---|
| Year 1 (2027) · child age 2 | +$2,000.00 | $37,000.00 | $41,500.00 |
| Year 2 (2028) · child age 3 | +$1,900.00 | $44,000.00 | $51,000.00 |
| Year 3 (2029) · child age 4 | +$1,800.00 | $51,000.00 | $60,500.00 |
| Year 4 (2030) · child age 5 | +$1,700.00 | $58,000.00 | $70,000.00 |
| Year 5 (2031) · child age 6 | +$1,600.00 | $65,000.00 | $79,500.00 |
Synthetic scenario output.
| Baseline | With a second child | |
|---|---|---|
| Usable house fund at year 5 | $79,500.00 | $65,000.00 |
| Healthy price at year 5 (20% down) | $397,500.00 | $325,000.00 |
| Fund low point | — | $37,000.00 in year 1 (2027) (not exhausted) |
Synthetic second-child scenario note.
Read plainly: with the v2 baseline — invested returns, raises outpacing expenses, and Leo's childcare step-down — a second child in year 2 (2028) no longer empties the fund, but it still takes the house off the table inside five years: the fund ends at $65,000.00 instead of $79,500.00. Making both work means changing an input, not a rounding error: cheaper childcare, more income, a later arrival, a later house, or some of each. Those inputs live in the scenario parameters — adjust them in chat and this page recomputes.