Just phase it in over time. Nominate a particular date, then make any new dutiable transaction involving freehold land exempty from transfer duty (Titles can put an administrative advice on title to show the particular land has come into the new system). After settlement, you pay quarterly land tax. Rather than a complete residential exemption, we can just exempt part of the taxable value from the assessment. No tiering, just flat rate the same way rates are determined. That way nobody gets stung paying the “new” land tax on a property they paid transfer duty to acquire.