The full property value is the taxable property value or the contract price, whichever is higher. The land value only matters for a perpetual right, because that is what article 13(f) of the CIMT applies its 20% to.
The sum follows paragraphs (d) to (j) of article 13 of the CIMT and returns the taxable value of each right, not the tax. The IMT rates and the stamp duty headings are in their own calculators, and the compensation at the end of a fixed-term right follows the rules on unjust enrichment, which depend on the facts.
An educational estimate from the figures you enter. It does not replace the tax authority’s own valuation or advice from a lawyer.