What happens when this goes wrong?
Every other page shows this payment working. Here you choose what breaks, and follow the damage — because a hold, a return or a missed cut-off is the system working as designed, and reading one calmly is the job.
Pick a failure above. Nothing here is invented — each one is a reason code this rail really uses, at the step where it really strikes.
FAST clears in real time through SACH but settles deferred-net in MEPS+ at MAS; this diagram shows a single net settlement leg and abstracts the exact number and timing of daily settlement files, plus the detailed screening and validation checks. Every failure here is authored on FAST (Fast And Secure Transfers), with the sources that back it.