The three-day cycle, day by day
Day one: your payment file is submitted into the Bacs system before your provider’s cutoff. Day two: the banks process and exchange the payment. Day three: the money arrives in the recipient’s account, usually by the start of the working day.
Working days only. A Bacs payment submitted on a Friday lands on Tuesday; submit it before a bank holiday weekend and it lands on Wednesday. If a payment absolutely must arrive on a specific date, count backwards three working days and add a margin for your provider’s cutoff time.
Why anyone still uses a three-day rail
Because it is cheap, batch-friendly and predictable. Bacs Direct Credit is how most UK salaries and supplier runs are paid: you submit one file, thousands of payments land on a known date, and the per-payment cost is pennies. Direct Debit runs on the same rail in the other direction.
Speed is not the only property that matters in a payment rail. For a payroll run known two weeks in advance, arrival on a guaranteed date beats arrival in twenty seconds.
When three days is too slow
Faster Payments settles in seconds to minutes for most payments and runs around the clock, with a scheme limit of £1 million per payment (individual banks often set lower limits). CHAPS settles the same working day with no upper limit, for a fee, and is the standard rail for property completions and other high-value transfers.
A well-routed account simply picks the right rail per payment: Bacs for the scheduled run, Faster Payments for the urgent invoice, CHAPS for the seven-figure completion. That choice is exactly what a routing engine automates.