Use-cases hub
Real-World Money Decisions — Solved
Every use-case answers a specific question a US professional, freelancer, or business owner actually asks. The math behind the answer. The calculator to run your numbers. 20 scenarios covering retirement, tax, housing, debt, business, and equity comp.
20 real-world money scenarios
Specific answers to specific questions
Each use-case takes a common US financial question — “How much do I need to retire at 50?” “Should I refinance?” — and walks through the answer with the right calculator. All 2026 IRS / SSA current.
01 · Retirement
Monthly Savings to Reach $1M by 65
Exact dollar amount to save each month — by current age and rate.
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02 · Retirement
Maximize Your 401(k) Employer Match
Stop leaving free money on the table. Find your max match dollar.
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03 · Housing
Monthly Payment on a $300K Mortgage
Principal, interest, PMI — the full picture by rate and term.
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04 · Housing
True Monthly Cost of a $500K Home
PITI + maintenance + utilities. The realistic homeownership cost.
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05 · Retirement
Retirement Corpus for $50K Annual Expenses
The 4% rule applied to your actual lifestyle.
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06 · Retirement
Retiring at 50: How Much Do You Need?
35-year retirement window with sequence-of-returns risk.
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07 · Tax
Federal Tax on $150K Salary (Single)
Effective rate, marginal bracket, AMT triggers.
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08 · Tax
Take-Home Pay on $100K in California
Federal + 9.3% CA + FICA — what actually hits your bank.
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09 · Tax
Capital Gains Tax on $50K Stock Sale
Short-term vs long-term, federal + state combined.
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10 · Equity
RSU Tax Surprise on $200K Vesting
The supplemental 22% withholding under-withholds for high earners.
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11 · College
Monthly Savings for Kid’s College in 18 Years
State-tax-deductible savings target by school type.
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12 · Business
ROI on $10K Marketing Campaign
CAC, payback, LTV — the unit economics test.
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13 · Mortgage
Should I Refinance My 5% to 6% Mortgage?
When the math says no — and the right break-even formula.
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14 · Retirement
Roth Conversion at 60 — Worth the Tax?
Partial conversions in low-income gap years.
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15 · Retirement
Backdoor Roth IRA on $250K Salary
Four steps to bypass the $161K Roth income cap legally.
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16 · Healthcare
HSA Triple-Tax Strategy
The most efficient retirement account in America.
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17 · Debt
Pay Off Debt or Invest the Difference?
The 6% threshold rule that decides for you.
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18 · Retirement
Mega Backdoor Roth for Tech Employees
Pump $46K/year extra into a Roth via after-tax 401(k).
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19 · Tax
Quarterly Tax on $200K 1099 Income
Safe-harbor rule + the 35%-into-HYSA framework.
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20 · Business
S-Corp Salary vs Distribution
Split $200K profit to save $18K in SE tax (legally).
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