Reading room
Guides from the ledger.
Last reviewed July 14, 2026
The calculators show you what the numbers are. These guides explain why the numbers behave the way they do — and, more usefully, when the obvious answer is the wrong one.
Each guide is written against primary sources: the statute, the regulation, or the agency handbook that actually sets the rule, rather than another site's summary of it. Sources are listed at the foot of every piece so you can check them. Each one pairs with a tool on this site, so you can read the idea and then test it against your own loan.
Paying down the loan
The loan you already have is the one you have the most control over. These pieces cover every lever you can pull on it — and what each one really costs.
Recast, refinance, or prepay: three ways to change a loan you already have
Three tools, three different jobs. One of them costs you six figures in interest and is routinely recommended as though it were free.
Read the guide →Biweekly mortgage payments: the trick, the fee, and the free version
The savings are real. The product sold to deliver them is not necessary, and the version that costs nothing does the same job.
Read the guide →Pay off the mortgage early, or invest the money?
The comparison nearly everyone makes — mortgage rate against expected stock returns — is the wrong one, and it is wrong in a direction that flatters investing.
Read the guide →How to actually get PMI removed: the request, the appraisal, and the stall
Federal law gives you three separate rights. They trigger at different times, and the one that rewards your extra payments is the only one you have to ask for.
Read the guide →How extra mortgage payments actually work
Why a dollar of extra principal saves more than a dollar, why timing matters more than amount, and the honest case for not prepaying your mortgage.
Read the guide →How PMI works and when it goes away
What private mortgage insurance actually covers, what it costs, the three ways to get rid of it, and when paying PMI is a perfectly rational choice.
Read the guide →Tax and the mortgage
What the deduction is worth, who it is worth it to, and why the answer for most households is nothing at all.
Choosing the loan
Decisions made before you sign, where the arithmetic is least forgiving.
Reference
Two pages underpin everything else here. The mortgage glossary defines the vocabulary — APR against note rate, points, escrow, PMI, recasting — in plain language. The calculation methodology sets out every formula and assumption used on this site, so that any figure published here can be checked rather than taken on trust.