Integrate an instant account verification provider (via Plaid Auth, Finicity, or a bank-direct verification network) as the primary verification path; when a customer submits their routing and account number, first attempt instant verification to receive immediate confirmation of account validity and ownership
Detect cases where the institution is not supported by the instant verification provider (small banks, credit unions, or institutions blocking data access) and fall back to prenote ACH verification automatically, notifying the customer that verification will take up to three banking days
For the prenote path, originate a zero-dollar ACH entry with SEC code matching the anticipated live entry type (PPD for personal accounts, CCD for business accounts); record the origination date and compute the soonest permissible re-origination date as three banking days after the prenote settlement date
Build a verification state machine with states: pending_instant, instant_verified, prenote_pending, prenote_verified, prenote_returned, and failed; transition states based on instant verification response, prenote return window expiry (no return = verified), or return code receipt
Gate payment origination on reaching a verified state; for prenote_pending accounts, queue intended live payments and release them automatically when the state transitions to prenote_verified after the return window closes
Store verification metadata (method used, verification date, and for instant verification the report identifier) alongside the account record for audit and compliance purposes
Known gotchas
Prenote verification confirms routing and account number validity at the RDFI but does not verify account ownership — a fraudster who provides a valid account number belonging to another person will pass prenote without any indication of fraud; instant verification with ownership confirmation is necessary for consumer debit use cases under NACHA account validation rules
NACHA's 2021 account validation rule requires originators of WEB debit entries to validate account validity using a commercially reasonable method before the first debit; prenote alone is generally accepted as sufficient, but only if the entry is not a WEB debit — for WEB debits, a more rigorous validation method may be required by your ODFI
Instant verification tokens and session data from providers like Plaid have short validity windows; if you cache the token and attempt to use the account data days later without re-verification, the session may have expired and the underlying account data may be stale
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