What is a book transfer?
Money that never leaves the platform — instant, free, and still fully double-entry.
A book transfer moves money between two accounts held at the same institution or platform. Because the money never leaves for an external network, it settles instantly and costs nothing.
Why it matters
Much of what a treasury platform does is internal: sweeping float to an operating account, moving funds between a customer's sub-accounts, advancing capital against collateral the platform already holds. Routing those through ACH or a wire would be slow and wasteful. A book transfer is the right tool.
Still fully accounted for
Instant and free doesn't mean invisible. On DigitalTreasury a book transfer posts to the double-entry ledger under the exact same rules as any external payment — balanced entries, integer cents, append-only — so the books explain it the same way they explain a wire.
ACH vs. wire transfer: what's the difference?
Both move money bank-to-bank — but speed, cost and reversibility make them very different tools.
Double-entry accounting for software platforms
Why the 500-year-old accounting model is exactly right for a modern payments ledger.
What are virtual accounts?
Give every customer their own account number on one real account — so inbound money self-attributes.