Question in regards to Vaping/ E-Cigarette and custom.

In reply to your first question, it all depends

In the good case, when you check in for your first flight, you will get multiple boarding passes - so if we guess you are in the US, you will get one for US->Singapore, and then another for Singapore->Malaysia. Your bag will then be marked as having an end destination of Malaysia. In this case you will never enter Singapore - you're just in transit, and never go through customs. You don't see or have access to your luggage until you get to Malaysia.

In the bad case, the check in agent is unable to check you all the way through, and you just get a boarding pass to Singapore. Its hard to predict when the bad case will occur, as sometimes the check-in agent just says they can't check you through. Or the computer won't let them, or some equally vague excuse. Booking your flights in two separate transactions will almost always result in the bad case. So will very long delays (>6 hours) between flights.

There is a place inside the airport called the "transit desk". Usually if you have only one boarding pass, you can go to the transit desk and get the next one issued, and they will deal with your luggage. This scenario is then equivalent to the good case. Note that you don't enter Singapore in this case, or go through customs - you stay inside the secure part of the airport.

In the bad case, if the transit desk does not work, You then have to collect your luggage, enter Singapore, and re-check in to Malaysia. Your bags will be subject to customs inspection at this point. If Singapore customs find prohibited items in your luggage, the penalty is up to a SG$10k fine or jail.

/r/singapore Thread