On RCI, sometimes you get a note, sometimes you don't. It will show up as a credit on your OB folio account about 2 days into the cruise. If you book directly with the cruise line & receive an OBC, it will show on your invoice. If a TA is giving you an OBC, the TA may state it on their invoice, but RCI will know nothing until the TA applies the OBC to your reservation (usually after final payment). If the OBC is through a TA, even if you take the paperwork with you, unless the Miami office has a record, the purser's office will not give you the OBC. You have to take that up with the TA once you arrive home. I have learned this from prior experience. I wasn't happy at the time, but all worked out well in the end.