Banks and credit

Lenders publish the arithmetic they use, and most of it is duller and more specific than the phrase “interest rate” suggests. This section reads it the way the lender computes it: the balance a card issuer actually charges against, the day a promotional period ends and what happens to the balance that survives it, what a deposit schedule commits a bank to and what it only advertises. Where a figure comes from a filing or a supervisory report, the document is named.

What that comes to in practice is a short list of narrow questions: which balance a card issuer multiplies by a daily rate, how many months a borrower must keep a loan before prepaid interest pays for itself, how long the yield printed on a statement lags the policy rate, and what happens to a debt when the lender is closed. Each is answered from a published rule — a billing-cycle definition, a tax topic, a rate schedule, a receivership process — and the rule is named in the text instead of being summarised from a press release.