How we research our guides

This page describes where the information in our guides comes from, which sources we treat as authoritative, and what we do when the authoritative sources disagree or are silent.

#The source hierarchy we use

1. Primary law and regulation. For questions about rights and obligations, the statute or regulation is the top of the hierarchy — the Fair Credit Reporting Act for credit reporting, the Truth in Lending Act for disclosure of borrowing costs, the Internal Revenue Code and Treasury regulations for tax treatment.

2. Official agency guidance and data releases. For figures that change annually, we use the agency's own release: IRS newsroom announcements and revenue procedures for contribution limits, standard deductions and tax brackets; Social Security Administration fact sheets for benefit and wage-base figures; the FDIC for deposit insurance limits; the Federal Reserve for published rate data.

3. Consumer-facing regulator explanations. The Consumer Financial Protection Bureau, the Federal Trade Commission and the SEC's investor education program publish plain-language explanations of the rules they enforce. These are excellent for describing how a process works in practice — what a dispute must contain, what a lender must disclose — and we lean on them heavily.

4. Peer-reviewed research and official statistics. For empirical claims about behavior or outcomes, we prefer published research and official statistical series over industry surveys, which are frequently produced by firms with an interest in the result.

5. Institution documentation. Product mechanics — how a specific account type works, what a plan permits — come from the institution's own documentation, clearly identified as such.

We do not build guides on top of other personal finance blogs, aggregated "top ten" pages, or content whose own sourcing we cannot inspect.

#Which figures we state, and which we do not

Some numbers are stable enough to state plainly: the mechanics of amortization, the structure of a credit score's components, how compounding works. Others change every year, and stating them without context creates a page that quietly becomes wrong.

For time-sensitive figures we do three things. We state the tax or plan year the figure belongs to. We name the body that sets it. And we link to that body's page, so a reader arriving two years later can find the current number in one click rather than acting on a stale one.

#Handling uncertainty and disagreement

When sources conflict, we say so and explain the nature of the disagreement rather than picking the answer that makes for a cleaner sentence. This happens most often with rules of thumb — how many months of expenses an emergency fund should hold, what share of income should go to housing — where competing benchmarks exist and none is authoritative.

When something depends on facts we cannot know, we identify the variable that decides it. "Whether to pay off a 6% loan or invest instead" has no general answer; it depends on the guaranteed nature of the debt return, your tax situation, your employer match and your tolerance for carrying the balance. The useful contribution is naming those, not asserting a conclusion.

When we are estimating, we label it. Calculator outputs are described as estimates, the simplifying assumptions are listed, and we state what real-world factors the model omits — fees, minimum balances, promotional rates, tax treatment, underwriting rules.

When we do not know, we say we do not know, and point to who does.

#What our calculators do and do not model

Every calculator on this site runs in your browser using JavaScript. No input is sent to us or to anyone else; there is no server processing involved and nothing is stored.

The models are deliberately simple, because a transparent model whose behavior you can predict is more useful for learning than an opaque one with more parameters. Specifically, our calculators assume monthly compounding, constant rates for the whole period, contributions or payments made at regular monthly intervals, and no fees or taxes unless explicitly stated. Real accounts differ on every one of those points.

They are intended to show the shape of a decision — whether a change is large or trivial, which direction a lever moves — not to produce a number you should rely on. Confirm exact figures with the institution involved.

#Editorial review

Every guide is reviewed against the checklist in our editorial policy before publication, and re-reviewed when an underlying rule or figure changes. If you believe something on the site is wrong, our corrections policy explains how to tell us.