The window for using the ACH network to reverse WEB payments from a CONSUMER account is covered by NACHA rules §8.6.1 and §8.7.1. The adjusting entry (effectively, the return) must be available to the ODFI by the start of business on the first business day following the 60th calendar day after the Settlement date.
WEB entries should not be used for non-consumer transactions. CCD or CTX entries may be used, instead.
For CCD or CTX entries to a non-consumer account, the window is very short -- the return entry must be available to the ODFI at the start of business on the second business day after the Settlement Date.
But those windows only address when the transaction can be sent back using the ACH system. Each and every ACH transaction you put into the system is accompanied by your ODFI's warranty that it was authorized (your contract with the ODFI binds you to the ODFI if the warranty is breached). Quoting from the 2010 NACHA Operating Guidelines, page OG 44, "ODFIs must understand that the warranty language within the Rules is broad and does not limit itself to the period of time in which an RDFI can recover funds through the return of entries through the ACH Network. In other words, the ODFI's potential liability under the NACHA Operating Rules for a breach of warranty is not limited to the return time frames, but is, instead, limited only by the statute of limitations for breach of contract claims under the applicable state law. The ODFI's liability for breach of warranty may exist for up to seven years in some states."
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8