Query Unit's payment API to retrieve all ACH payments with status returned within a rolling 60-day window; use pagination to retrieve the full result set
Separate returns by category: administrative returns (R02, R03, R04 — account closed, no account, invalid account) and unauthorized returns (R05, R07, R10, R29); NACHA monitors each category against different thresholds
Compute the administrative return rate as the number of administrative returns divided by the total number of ACH debits originated in the same 60-day window; alert if this rate approaches the NACHA 3.0% threshold
Compute the unauthorized return rate using only R05, R07, R10, and R29 returns divided by total ACH debits; alert at the NACHA 0.5% threshold for unauthorized returns
When a threshold is approached, trigger a review workflow: identify the originating customers or payment corridors with the highest return rates and flag them for remediation
Generate a monthly return rate report in a format suitable for submission to your ODFI or for internal compliance review; include trend data to show whether rates are improving or deteriorating
Known gotchas
NACHA measures return rates over a rolling period from the ODFI's perspective, not the platform's; your calculations using Unit's API data should match what your ODFI sees, but request confirmation from your ODFI on the measurement window they apply
R07 (authorized revoked) and R29 (corporate customer advises not authorized) require specific documentation and response procedures beyond just monitoring the rate — receiving a cluster of these codes may indicate a fraud vector requiring immediate investigation
Unit's API returns payment records in the status they currently hold; a payment may transition through multiple statuses — ensure your return rate query uses the final settled status, not intermediate states
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