Same Day ACH will kick things up a notch in a few weeks as new rules take effect for debit transactions. Here's what's coming and what credit unions can do to get ready. On May 19, 2015, NACHA announced that it gave the green light to a three-phase implementation plan for Same Day ACH...On Sept.15, 2017, phase II kicks in, requiring credit unions to provide Same Day ACH debit capabilities, too. International ACH transactions and single transactions of more than $25,000 are excluded.