How Mortgage Amortization Works (and How Extra Payments Save Thousands)
See how each mortgage payment splits between interest and principal, why early payments are mostly interest, and how small overpayments shorten the loan.
Read the guideMortgages
Fixed vs Adjustable-Rate Mortgage: Which One Fits You?
How fixed and adjustable-rate mortgages work, what rate caps mean, and a simple way to decide based on how long you plan to keep the loan.
Read the guideWhen Does Refinancing Make Sense? The Break-Even Rule
Use the break-even point to judge a refinance: compare closing costs with monthly savings, watch the reset term, and avoid the common traps.
Read the guideRent vs Buy: How to Run the Numbers Honestly
Compare renting and buying on total cost, not the monthly payment: unrecoverable costs, the 5% rule, time horizon and the value of flexibility.
Read the guideDebt
Debt-to-Income Ratio: What Lenders Look For
What front-end and back-end DTI mean, how to calculate yours, the ranges lenders commonly use, and practical ways to bring the ratio down.
Read the guideDebt Avalanche vs Debt Snowball: Which Payoff Plan Works Better?
A worked example of both debt payoff methods, how much interest each saves, and how to pick the one you will actually stick with.
Read the guideHow Credit Card Interest Is Calculated (APR, Daily Rate and Grace Periods)
Understand APR, the daily periodic rate, average daily balance and the grace period, and see why minimum payments keep you in debt for years.
Read the guideInvesting
Compound Interest Explained, with the Rule of 72
How compounding works, why starting early beats saving more later, the Rule of 72 shortcut, and how fees and inflation eat into growth.
Read the guideRetirement
401(k) vs Traditional IRA vs Roth IRA: 2026 Limits and How to Choose
The 2026 contribution limits, how traditional and Roth tax treatment differ, and a simple order for funding your retirement accounts.
Read the guideHow Much Do You Need to Retire? The 4% Rule Explained
Turn your retirement spending into a savings target with the 4% rule, understand its limits, and adjust for pensions, Social Security and inflation.
Read the guideTax & Pay
Gross vs Net Pay: How to Read Your US Paycheck
Every line between gross pay and take-home pay: federal and state withholding, Social Security, Medicare, pre-tax and post-tax deductions.
Read the guideUS Tax Brackets for 2026: Marginal vs Effective Tax Rate
The 2026 federal tax brackets and standard deduction, a worked example, and why a raise never lowers your take-home pay.
Read the guideUK Stamp Duty Explained, Including First-Time Buyer Relief
Current Stamp Duty Land Tax bands in England and Northern Ireland, first-time buyer relief, the surcharge on additional homes, and worked examples.
Read the guideUK Income Tax and National Insurance 2026/27: How Your Take-Home Pay Is Worked Out
The 2026/27 Personal Allowance, tax bands and employee National Insurance rates, with a step-by-step take-home pay example and the £100,000 trap.
Read the guideBudgeting
How Big Should Your Emergency Fund Be?
How to size an emergency fund from your essential costs, where to keep it, how to build it from zero, and when to use it.
Read the guideHow we write these guides
Every guide explains one decision from first principles, shows the arithmetic with a worked example, and states the assumptions behind it. Where a guide quotes tax bands, contribution limits or thresholds, they are checked against official sources such as the IRS, GOV.UK and HMRC, and the date of the last update is shown at the top of the page.
The guides are general information, not personal advice. If you spot a figure that has changed, please tell us and we will correct it.