One Point Nine Billion That Was Never There - reconciliation, breaks, and how long to wait for a twin

A shop’s own book on the left, the bank’s statement on the right, and a line from each entry to its twin. Most lines are solid. Card payouts are dashed, because they land days late. One entry has no line at all.

Before you start. From Every Litre Leaves One Tank and Enters Another - double-entry, normal balances and the trial balance: every movement is a pair of entries, so a book can add up and still be wrong about the world. From A Book You Never Erase - the append-only ledger, reversals and derived balances: a book is only ever added to, so a mistake is corrected by a new entry, not by rubbing out. Four Parties to Every Tap - issuer, acquirer, network and interchange and The Hold That Is Not Money Yet - authorisation, capture, clearing, settlement and chargebacks explain why card money arrives days after the sale, which is the lateness this lesson has to live with.