Do I need to have all my assets in FL necessarily?

No, in order to qualify for the LDF a "relevant property" (as defined in the MOU) must have been acquired in Liechtenstein. This can be either a bank account and/or an entity/structure managed out of Liechtenstein. So in theory only very little money needs to be actually in Liechtenstein in order to declare and disclose assets to HMRC. There are certain restrictions but generally speaking a UK tax payer who has undeclared funds in another jurisdiction can take advantage of the LDF. The main exception is a person having at the date of signing of the MOU an offshore bank account that was opened through a UK branch or agency. They will not in relation to that account be eligible for the shorter limitation period, the fixed penalty and composite tax rate under the LDF.