Our authorities expect that one of the reasons for anyone wanting to become Maltese citizens is their affinity to the island. And such affinity normally translates to one wanting to reside in the national country and enjoy all the benefits that such citizenship entitles you to.
On the other hand, being a Maltese citizen does not mean entrapment within our shores. Our authorities realise that any entrepreneur with large investments overseas will translate to substantial periods of absence from our island. And our authorities actually encourage overseas trade since this enhances our own national wealth.
Therefore there is no expectation that one is resident throughout the year. But a regular period of local residency, even if a short one, is expected.