Check Image Clearing (Check 21 / X9) — impact tolerance ≤ 1 business day — ITOL

Impact tolerance: ≤ 1 business day — measured against the cash-letter schedule, not the wall clock. The tolerance is breached when items can no longer make the next unexpired cash-letter deadline that keeps Reg CC availability and return timelines intact. One business day is the outer bound. (illustrative default — trace the derivation, then replace with your own harm analysis)

Definition: Capture, exchange, and settle paper check items as electronic images via Federal Reserve check services and correspondent image-exchange partners under Check 21.

Why it is designated: Check 21 image exchange remains the settlement rail for consumer and business checks. Missing a cash-letter window breaches availability commitments under Reg CC (the federal funds-availability rule) and return-item timelines (the midnight deadline). That drives customer complaints and float losses.