[Image Source: ILR Validation Rules 2023-24 Version 4 Published 24/01/2024]
An "AFinDate_03" ILR validation error will be triggered, if there are any "Paid" PMR 'Payment Record' for the learner (with a Status of "Paid", a "Paid Date", and an "Actual Amount"), where the "Paid Date" is still in the future.
The "File Preparation Date" refers to the day on which your ILR export file was generated.
You're not allowed to report in the ILR that a PMR will be "Paid", on a date that is still in the future -- you must only report PMRs as "Paid" once the payment has been made.
This error can also be triggered by reporting a TNP 'Total Negotiated Price' with an "Effective Date" that is still in the future.