The forecaster runs tomorrow before tomorrow does

Open an account and ask what it will do over its life. The Forecast panel runs the account forward to its maturity date and shows one projected transaction per row: the instalment falling due, the collection that clears it, the day’s interest, the notice paying out. Nothing is written. Nothing reaches the ledger. Running it changes no balance.

What makes the answer trustworthy is that it is not a separate calculator. The forecast runs the account through the same end-of-day processing the account goes through every night: the same schedules, the same day count, the same business-day rules, over days that have not happened yet. A test proves it. Take 100,000 at 10%, accruing on one convention for two days and another from the third after a change dated mid-window. Forecast five days, then let five nights process. The five projected accruals equal the five booked accruals to the cent, including the two either side of the switch.

The projection starts from the day after the account’s last processed day and from today’s real balances, so it never replays history. A payment booked with a future value date is not history yet: a deposit of 100 value-dated 10 June appears as a row in a forecast run to 15 June. A loan of 100,000 with an instalment of 1,500 collected by debit order shows two rows on the due date, the instalment falling due and the 1,500 received, because the account arranges that collection and the nightly run raises it.

That is what it is for. Add a simulated deposit of 100,000 to an empty call deposit and watch the daily interest fill in on the account’s own day count. Stage a rate change or a revised instalment plan in the studio and the forecast projects from the account as it would be once the change applies, so the person who countersigns sees the same effect before anyone commits it. Check a new account type against the forecaster before it goes live. The full mechanics, including what the nightly run does that the forecast does not, are in the guide article on forecasting an account.