The catalog, cut the way you buy.

The hardest math in the catalog: AMT on an ISO exercise to the share, QSBS §1202 across all four regimes, 83(b) elected vs. not, wash sales, and the retirement-income cliff stack. Federal, planning-grade, exclusions published.

For: equity-comp & tax platforms, startup-employee tools, advisors with founder clients

RMDs, Roth conversions and the backdoor, Social Security timing, 401(k) match math, FIRE, plus the household engine's coordinated drawdown strategies when one answer isn't enough.

For: retirement platforms, 401(k) providers, advisory firms

Mortgages end to end: points break-even, PMI removal, ARM vs. fixed, biweekly, refinance. Plus auto loans, loan comparison, student loans, payoff strategies, and credit-card minimum-payment math.

For: lenders, credit unions, personal-finance apps, real-estate platforms

Burn and runway, SAFE dilution checked against Y Combinator's own worked examples, option-pool math, equipment lease vs. buy, SBA loan cost from the statute and the current fee notice.

For: founder-facing fintech, banking-for-startups, cap-table tools

Longevity horizons on SSA life tables, annuity payouts, life-insurance need, long-term-care and eldercare cost math, and the longevity-aware Monte Carlo that carries them into a whole-household plan.

For: insurers, annuity platforms, retirement advisors

Federal estate and gift exposure, step-up vs. gift-now basis math, the inherited-IRA 10-year rule, QCDs against the current-year cap, and 529 superfunding, all anchored to the statute, with wills, trusts, and probate as published exclusions. Computation, never legal advice.

For: advisors and institutions serving households across generations

Relocation, a child, a wedding, a sabbatical, one income, a windfall, a renovation, plus 529 savings and private school. The everyday decisions a consumer-facing product has to answer.

For: personal-finance apps, banks, employers' financial-wellness programs