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When the Check You Converted Doesn’t Meet the Rules
One of the convenient features of ACH processing is the ability to convert paper checks into electronic payments, allowing businesses to save time and get paid faster. But not every check is eligible for conversion, and if the source document (the original check) doesn’t meet the required standards, the transaction can get kicked back.
That’s when you’ll see ACH Return Code R39.
Let’s dive into what R39 – Improper Source Document means, what typically causes it, and how you should handle it when it comes up.
What Does ACH Return Code R39 Mean?
ACH Return Code R39 stands for:
“Improper Source Document.”
Here’s NACHA’s official definition:
R39 – Improper Source Document: The source document used to initiate an ACH entry (such as a check) did not meet the requirements for conversion under ACH network rules.
In simple terms: the paper check you tried to convert into an ACH payment wasn’t eligible for conversion, either because of its content, condition, or type.
What Makes a Source Document “Improper”?
ACH rules specify what types of checks can be electronically converted. A source document may be considered improper if:
It was not a consumer check (e.g., a money order, cashier’s check, or business check)
It was illegible, altered, or incomplete
The check was post-dated or stale-dated
The check didn’t include the proper authorization for conversion
The amount on the check didn’t match the ACH entry
The check was already used for another transaction (duplicate)
The account holder did not consent to the check’s electronic conversion (where consent is required)
If the document doesn’t fit the rules, the receiving bank is obligated to reject the ACH entry.
How to Handle ACH Return Code R39
Here’s how to respond if you get an R39 return:
1. Review the Original Check
Pull up the scanned image or physical check associated with the returned ACH transaction. Look for signs of ineligibility: was it the wrong type of document, damaged, altered, or improperly authorized?
2. Determine Why the Check Was Ineligible
- If it was the wrong type of check (e.g., a business check when only consumer checks are allowed), you’ll need a different payment method.
If the check was missing information or improperly converted, you’ll need to correct your processes.
3. Contact the Customer (If Appropriate)
If needed, reach out to your customer to either request a new payment or clarify whether they consented to electronic conversion. They may prefer to issue a new check or pay another way.
4. Deposit the Paper Check (If You Still Have It)
If the original paper check is still in your possession and valid, you can often deposit it manually through traditional banking channels.
5. Update Your Check Conversion Procedures
If the error came from your scanning, authorization, or eligibility verification process, it’s a good time to tighten up your internal checks.
How to Avoid R39 Errors in the Future
To minimize R39 returns:
Train staff on eligible vs. ineligible checks for ACH conversion
Use high-quality scanning equipment and check images for legibility
Make sure customers provide authorization if required
Screen checks carefully before converting—no money orders, no heavily altered documents
Use ACH processing systems that help validate source documents automatically
Building a careful check conversion process helps protect your business from returns and compliance issues.
Get ACH Processing With Durango
ACH Return Code R39—“Improper Source Document”—means the check you tried to convert into an electronic payment didn’t meet ACH standards. Whether it was the wrong type of check, an authorization issue, or a formatting problem, the fix often starts with better document handling and eligibility checks.
At Durango Merchant Services, we help businesses manage all aspects of ACH processing—from traditional entries to check conversions—with smart systems, expert advice, and practical tools to minimize returns like R39.
