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Financial glossary
Plain-English definitions of every term used across our calculators and guides — with concrete examples.
36 terms
- 25× Rule
- The corollary to the 4% rule: your retirement portfolio target is 25 times your annual expenses.
- Example: Spending $50,000 per year requires a $1,250,000 portfolio to retire safely.
- 4% Rule
- A retirement withdrawal guideline stating that withdrawing 4% of your portfolio in year one (then adjusting for inflation) historically sustained a 30-year retirement.
- Example: A $1,000,000 portfolio supports $40,000 in year-one withdrawals, rising with inflation each year.
- 401(k)
- An employer-sponsored retirement account that lets employees contribute pre-tax dollars (or post-tax in a Roth 401(k)), often with an employer match.
- Example: Contributing $10,000 to a traditional 401(k) reduces your current taxable income by $10,000.
- Amortization
- The schedule by which a loan is paid down, with each payment split between interest (front-loaded) and principal (back-loaded).
- Example: On a $300,000 30-year loan at 6%, year-one payments are ~83% interest; by year 25, they're ~83% principal.
- APY (Annual Percentage Yield)
- The effective annual rate of return on a deposit account, accounting for the effect of compounding.
- Example: A 4.4% nominal rate compounded daily produces an APY of ~4.50%.
- Asset Allocation
- The mix of asset classes (stocks, bonds, cash) in a portfolio, calibrated to balance risk and return for the investor's timeline.
- Example: A common starting point: 110 minus your age = stock percentage. At 30, that's 80% stocks, 20% bonds.
- Backdoor Roth IRA
- A legal strategy that allows high earners above Roth IRA income limits to contribute by first making a non-deductible Traditional IRA contribution, then immediately converting it to a Roth IRA.
- Example: A single filer earning $200K (above the $161K Roth phase-out) contributes $7,000 to a Traditional IRA, then converts it to a Roth IRA the same week — paying no additional tax if there are no other pre-tax IRA balances.
- Catch-Up Contribution
- An extra contribution amount the IRS allows for people aged 50+ to help boost retirement savings later in their career.
- Example: A 55-year-old can contribute an extra $7,500 to a 401(k) on top of the regular limit.
- Compound Interest
- Interest calculated on the initial principal plus all accumulated interest from previous periods, causing exponential rather than linear growth.
- Example: $10,000 at 8% compounded annually grows to $21,589 in 10 years, vs $18,000 with simple interest.
- Contribution Limit
- The maximum amount the IRS allows you to contribute to a specific tax-advantaged account in a given calendar year.
- Example: The 2026 401(k) employee deferral limit is $24,000; contributions above that are not tax-deductible.
- Debt Avalanche Method
- A debt payoff strategy where you pay off debts from highest interest rate to lowest, minimizing total interest paid over the life of the debts.
- Example: A 24% APR credit card is paid before a 6% student loan, even if the credit card has a larger balance.
- Debt Snowball Method
- A debt payoff strategy where you pay off debts from smallest balance to largest, ignoring interest rates, to build psychological momentum from quick wins.
- Example: With debts of $500, $3,000, and $12,000, you attack the $500 first regardless of which has the highest APR.
- Diversification
- Spreading investments across many assets to reduce the impact of any single one performing poorly.
- Example: Owning the S&P 500 instead of one stock means a single bankruptcy costs you ~0.2%, not 100%.
- Dollar Cost Averaging (DCA)
- An investment strategy where you invest a fixed amount of money at regular intervals regardless of market price, smoothing out the cost basis over time.
- Example: Investing $500 per month into an index fund every month for 12 months, regardless of whether the market is up or down.
- Emergency Fund
- Cash reserved in a liquid, low-risk account to cover unexpected expenses or income loss without resorting to debt.
- Example: A household with $4,000 monthly expenses targeting 6 months needs $24,000 in a HYSA.
- Employer Match
- A contribution your employer makes to your 401(k) based on what you contribute, typically up to a percentage of your salary.
- Example: A 100% match up to 5% of salary on a $80,000 income is a free $4,000 per year.
- Expense Ratio
- The annual fee a fund charges shareholders, expressed as a percentage of assets, deducted automatically from returns.
- Example: A 1% expense ratio on a $100,000 portfolio costs $1,000 per year, even in a losing year.
- FDIC Insurance
- U.S. government insurance that protects bank deposits up to $250,000 per depositor, per bank, per ownership category, in case the bank fails.
- Example: A married couple at one bank has $500,000 of joint coverage ($250k each) plus more across individual accounts.
- FIRE (Financial Independence, Retire Early)
- A movement focused on aggressive saving and investing to reach financial independence — typically 25× annual expenses — well before traditional retirement age.
- Example: Saving 50% of a $80,000 income can reach FI in roughly 17 years, vs 40+ years at a 10% rate.
- High-Yield Savings Account (HYSA)
- An FDIC-insured savings account, typically offered by online banks, paying interest rates significantly higher than the national savings average.
- Example: A 4.5% APY HYSA on a $20,000 emergency fund pays ~$900/year in interest, vs ~$90 at a brick-and-mortar bank.
- HSA (Health Savings Account)
- A triple-tax-advantaged account paired with a high-deductible health plan: tax-deductible contributions, tax-free growth, and tax-free withdrawals for qualified medical expenses.
- Example: Maxing an HSA at $4,300/year for 30 years at 8% with no withdrawals grows to ~$487,000.
- Income-Driven Repayment (IDR)
- Federal student loan repayment plans that cap monthly payments at a percentage of discretionary income, with forgiveness of remaining balance after 20–25 years.
- Example: A SAVE-plan borrower earning $50,000 might pay ~$200/mo regardless of total balance.
- Index Fund
- A mutual fund or ETF that passively tracks a market index like the S&P 500, holding the same securities in the same proportions as the index.
- Example: Vanguard's VOO tracks the S&P 500 with a 0.03% expense ratio — $3 per year per $10,000 invested.
- Liquidity
- How quickly an asset can be converted to cash without losing significant value.
- Example: A HYSA is fully liquid (same-day transfer); a 401(k) is illiquid (10% penalty + taxes before 59½).
- Lump Sum Investing
- Investing the entire available amount in one transaction rather than spreading it across multiple deposits.
- Example: Receiving a $50,000 inheritance and investing all $50,000 into an index fund on the same day.
- Mortgage Prepayment
- Paying more than the required monthly mortgage payment, with the extra applied directly to principal to shorten the loan and reduce total interest.
- Example: Adding $300/mo to a $300,000 30-year mortgage at 6% saves ~$95,000 in interest and ends the loan ~7 years early.
- Opportunity Cost
- The value of the next-best alternative given up when making a financial decision.
- Example: Prepaying a 4% mortgage instead of investing in an index fund returning 8% has a ~4% annual opportunity cost.
- Pro-Rata Rule
- An IRS rule that requires Backdoor Roth conversions to be treated as a proportional mix of pre-tax and after-tax dollars across all Traditional, SEP, and SIMPLE IRAs.
- Example: If you have $60,000 in a pre-tax Traditional IRA and contribute $6,500 after-tax, then convert that $6,500, about 90% of the conversion is taxable because pre-tax balance dominates.
- Public Service Loan Forgiveness (PSLF)
- A U.S. federal program that forgives the remaining balance on Direct Loans after 120 qualifying monthly payments while working full-time for an eligible public-service employer.
- Example: A teacher with $80,000 in federal loans paying $300/mo on an income-driven plan can have ~$45,000 forgiven tax-free after 10 years.
- Roth IRA
- An individual retirement account funded with after-tax dollars, where qualified withdrawals in retirement are completely tax-free.
- Example: A $7,000 Roth IRA contribution at age 30, growing at 8% to age 65, becomes ~$103,000 — all tax-free.
- Rule of 72
- A mental math shortcut that estimates how many years it takes for an investment to double, by dividing 72 by the annual percentage return.
- Example: At 8% annual return, money doubles every 9 years (72 ÷ 8 = 9).
- Safe Withdrawal Rate
- The maximum annual percentage of a retirement portfolio that can be withdrawn without depleting the portfolio over a target retirement length.
- Example: The 4% rule — withdrawing 4% of an initial $1M portfolio ($40K) annually, adjusted for inflation, has historically lasted 30+ years.
- Sequence of Returns Risk
- The risk that the order in which investment returns are received will negatively impact a portfolio when withdrawals are being made, even if the long-term average return is the same.
- Example: Two retirees with identical 30-year average returns can end up with $0 vs $2 million depending on whether bad market years hit early or late in retirement.
- Simple Interest
- Interest calculated only on the original principal, with no interest earned on previously accumulated interest.
- Example: $10,000 at 8% simple interest earns a flat $800 every year, regardless of duration.
- Tax-Advantaged Account
- An account like a 401(k), IRA, or HSA that offers tax benefits — either deferring taxes on contributions or letting growth accumulate tax-free.
- Example: Maxing a $7,000 Roth IRA shelters all future gains on that $7,000 from taxes forever.
- Total Interest Paid
- The cumulative interest cost of a loan over its full term — the most useful single number when comparing mortgage options.
- Example: A $300,000 loan at 6% costs ~$348,000 in interest over 30 years vs ~$156,000 over 15 years.
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