FAQ Home   5113. The "Date value" generated in your application is "amended" while uploading to the BACS software. What is the reason?   The "UHL1 Date" in the BACS Standard 18 output will be VALIDATED & AMENDED by the BACS software based on the following four conditions : Format check - If the date is not in the format bYYDDD, it will be overridden with the current BACS processing date. Past processing day check - It must be the same as or later than the current BACS processing day, if not, UHL1 date will be overridden with the current BACS processing date. Valid processing day check - Date must be a valid processing day i.e., must not be a Saturday, Sunday, English bank/public holiday or other nonprocessing day. Processing window (31 days) - Date must be no later than 31 days after the current processing day.