The cost of transferring a property is rarely a simple percentage of what the buyer paid. It is calculated against an official reference value, and the difference between the two figures drives most of the confusion.
The reference value comes first
Authorities publish a minimum assessed value for land and buildings in each locality, updated periodically. It exists so that transfer duty cannot be avoided by under-declaring the sale price on paper.
The duty is calculated on whichever is higher, the declared consideration or the published reference value for that address and property type.
Where the reference value has not been revised for some years, it can sit well below actual market prices, and duty is then charged on the higher declared amount instead.
Duty and registration fees are separate charges
Transfer duty is a tax on the transaction. The registration fee is a charge for recording the transfer in a public register, and the two are set by different rules.
The registration fee is often a smaller percentage and sometimes capped at a fixed maximum, which means it stops scaling once a property passes a certain value.
Both are usually payable by the buyer, though local practice varies, and a contract can allocate them differently between the parties.
Property characteristics adjust the assessment
The reference value is not a single number for a district. It is modified by floor level, building age, construction type, frontage on a main road and whether the land is agricultural or converted.
Under-construction and completed properties are frequently assessed under different rules, since one transfers a right to receive a unit and the other transfers the unit itself.
These adjustments are why two apparently comparable flats in the same building can attract noticeably different assessed values and therefore different duty.
Concessions change who pays what
Many jurisdictions offer reduced rates for particular categories of buyer or particular kinds of transfer, and these concessions are typically conditional on holding the property for a period.
Transfers between family members, or by gift or inheritance, are often treated under a separate schedule with lower charges attached.
Because concessions are set locally and revised regularly, they are one of the parts of the calculation most likely to have changed since a buyer last transacted.
Why the final figure arrives late
The precise amount is confirmed only when the document is presented and the assessed value applied by the registering officer to the specific property described.
Any discrepancy in the description, such as measured area differing from recorded area, is resolved at that point and can move the figure.
Rates, reference values and exemptions vary by jurisdiction and change over time, so a professional familiar with the local register is the practical source for a specific transaction.