A date code (or date stamp) is an alphanumeric marking stamped or heat-embossed on the interior of a bag, typically on the lining or leather tab inside a pocket. It encodes information about where the bag was made and when — the specific format varies by brand and era.
Louis Vuitton's date codes are the most commonly referenced: from 1990, they use a two-letter factory code followed by four numbers (e.g., SD4041 = made in France, 40th and 41st weeks, 200[4]). Understanding the code format for a specific brand and era is an essential tool for authenticating pre-loved bags.
Limitations of Date Codes
Date codes are not serial numbers — multiple bags can share the same date code. More importantly, counterfeiters know date codes exist and can stamp convincing fakes. A correct date code does not authenticate a bag; it's one signal among many. Newer Louis Vuitton bags use RFID chips instead of stamped codes.