I just took a look at my Welcome Aboard booklet (that just happens to be sitting right next to me) and... the answer to your question is not there. I also checked ncl.com. I imagine you did both, also. Have you tried logging into your My NCL account? If you've indicated there that you plan to settle in cash, perhaps the amount will be shown. Let us know if that doesn't work and we can dig deeper. I would be certain, though, that the absolute minimum would be that needed to cover the daily service charge (now $12 per passenger per day), but, of course, it could be higher.