X9 File Requirements - Lead | API Docs

The sections below cover the file structure and the fields Lead uses for routing, matching, and funds movements.

File Structure

Each X9 file contains one or more cash letters, each of which contains one or more bundles of check items.
Each check item includes the front image, back image, and structured MICR data.
Do not mix forwards and returns in the same X9 file.

Key Fields

The following fields are critical for correct processing:

Field	Notes
Settlement Date	Lead uses this date to determine when to move funds between the Fed GL and the Checks In Process GL.
Amount	Integer value in cents. Lead uses this for daily limit checks and funds movements.
Routing Number	Lead uses this to route incoming checks to the correct partner. For dedicated routing numbers, Lead forwards all items on the routing number to you.
OnUs Field (MICR)	Contains the account number. Lead uses this for item matching on shared routing numbers. Lead works with each partner to configure the structure of this field.
ECE Institution Item Sequence Number	A mandatory 15-digit field. Lead uses this to match incoming returns to the original outgoing entry. Populate it consistently on all outgoing X9 files.
Return Reason	Populated on return items. Indicates why a check is being returned — for example, an account closed or fraud detected.
Cash Letter ID	An eight-character alphanumeric identifier for the cash letter within the file.
BOFD Indicator	Bank of First Deposit indicator. Mandatory field; valid values are Y, N, or U.

Return Matching

Lead matches incoming returns to original outgoing entries using the ECE Institution Item Sequence Number and the submission date. Populate this field consistently on all outgoing X9 files to enable accurate return matching.

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