For second homes, the first determination to charge a premium must be made at least 12 months before the beginning of the financial year to which the proposed premium relates.
Ar gyfer ail gartrefi, rhaid gwneud y penderfyniad cyntaf i godi premiwm o leiaf 12 mis cyn dechrau'r flwyddyn ariannol y mae'r premiwm arfaethedig yn berthnasol iddi.