Every Capital piece The Keep has published, grouped by the actual decision it helps you make — not by publish date. Start with the basics if you’re new, or jump straight to the math you actually need.
The basics, done right
Personal finance content usually starts with a rule of thumb and never checks whether the thumb was right. This section starts with the actual mechanics instead: how compound interest really works and why starting early beats starting big, worked with real numbers rather than a chart that conveniently curves upward; why treating all debt as “good” or “bad” is a category error that costs money, versus treating every debt as a cash-flow decision; the envelope budgeting method run against real income and real bills instead of a hypothetical; and lifestyle creep, the raise that quietly disappears into upgraded spending before it ever compounds into anything. None of these are new ideas. What’s different here is that each one gets the actual arithmetic instead of the slogan.
- Compound Interest, Explained Like You’re Actually an Adult — why starting early beats starting big.
- Why “Good Debt” Is a Lie That Keeps You Poor — treating all debt as a cash-flow decision, not a good/bad label.
- The Envelope Method, Real Math — budgeting worked through with actual numbers.
- Lifestyle Creep: The Raise You Never Actually Got — how a raise disappears before it compounds.
Big money decisions
Three decisions large enough that getting the framing wrong costs real money, not rounding-error money. Renting versus buying gets the actual break-even math — current mortgage rates and real closing and selling costs — instead of the flat five-year rule of thumb that ignores both. Financing a car versus paying cash gets worked against the real all-buyer average APR, not a best-case credit-tier number that understates what most people actually pay. And buy-now-pay-later gets checked against what it actually costs in late fees and credit-stacking risk, not the “basically free” framing the checkout button implies. Each piece ends with the actual number, not a rule that only works for the median case.
- Renting vs. Buying: The Real Break-Even Math, Not the Rule of Thumb — a full worked calculation, not the flat 5-year rule.
- Financing a Car vs. Buying Used in Cash — the real cost comparison — with a calculator for your own credit tier.
- Buy Now, Pay Later Isn’t Free Money — Here’s What It Actually Costs — the real late-fee/APR structure behind “basically free.”
Where your money actually goes
Five pieces about the money that’s already leaving before any investing decision even happens. A line-by-line breakdown of where a paycheck’s deductions actually go, not just the number that lands in the account. The marginal-versus-effective tax rate myth, worked through with the real 2026 bracket thresholds, that makes people think a raise can cost them money — it can’t, and the piece shows exactly why. What recurring subscriptions actually cost annualized, since a monthly number is built to be forgotten. The real math on credit card minimum payments, including the 1%-of-balance-plus-interest structure most issuers actually use, not just the flat-percentage version. And the 401(k) match’s “free money” framing, checked against vesting schedules and the auto-enrollment defaults that quietly leave money on the table for people who never opt up.
- Where Your Paycheck Actually Goes, Line by Line — the full deduction breakdown.
- Marginal vs Effective Tax Rate: The Myth That Makes People Turn Down Raises — why a higher bracket never shrinks your paycheck — with a bracket calculator.
- What Your Subscriptions Actually Cost You in a Year — the annualized real number.
- Credit Card Minimum Payments: The Real Math — how long minimum payments actually take, and cost.
- The 401(k) Match Is ‘Free Money’ — Except When It Isn’t — vesting schedules and the SECURE 2.0 exception.
Saving and investing, without the hype
The actual math behind saving and investing decisions, without a pitch attached to any of it. The real emergency fund number, calculated for an actual situation instead of the blind three-to-six-months rule. What a high-yield savings rate really nets after tax and inflation, since the advertised APY is never the number that matters. Index funds versus picking stocks, worked through the actual long-run data rather than either side’s talking points. What retail investors are occasionally positioned to notice before institutions are — a real, narrow edge, not a claim that beats professional money managers at their own game. And the HSA’s triple tax advantage, including the after-65 rule that quietly turns it into a second retirement account nobody advertises it as. Standard disclaimer applies throughout: this is general math, not advice for your specific situation.
- The Actual Emergency Fund Number, Not the Rule of Thumb — how to calculate your real number instead of guessing 3–6 months.
- High-Yield Savings Accounts: What the Rate Actually Nets You After Everything — the after-tax, after-inflation real return.
- Index Funds vs. Picking Stocks: What the Actual Long-Run Data Says — the long-run return data, not a hot take.
- What Retail Investors Notice Before Institutions Do — where individual investors actually have an edge.
- The HSA Triple Tax Advantage: Why It’s a Stealth Retirement Account — pretax in, tax-free growth, tax-free out, and what changes at 65.
This page indexes general-information content, not personalized financial advice. Consult a licensed financial advisor before making decisions specific to your situation.
The other two pillars have guides of their own: The Liberty Guide and The Coffee Guide.