According to § 33 ImmoWertV, the property-specific adjusted property interest rate is to be determined in accordance with § 21 Paragraph 2 ImmoWertV, taking into account § 9 Paragraph 1 Sentence 1 ImmoWertV and, if necessary, adjusted in accordance with § 9 Paragraph 1 Sentences 2 and 3 ImmoWertV.
For the calculation of the property interest rate (i), the formula(s) of the capitalised earnings method is used and this is converted to i. Market data is used for this purpose. n stands for the residual utilisation period. The formula for the property interest rate is shown below.
i = net income / (purchase price ± adjustment) - [((1 + i)^n * i) / ((1 + i)^n - 1)] * (1 + i)^-n * (purchase price - land value ± adjustment) / (purchase price ± adjustment)
If a standard market property has a value of 229,535.55 MU, a land value of 120,000 MU, a net income of 12,000 MU, a remaining utilisation period of 50 years, and a property-specific adjustment of 0, the following calculation results for our example.
i = 12,000 / (229,535.55 - 0) - [((1 + i)^50 * i) / ((1 + i)^50 - 1)] * (1 + i)^-50 * (229,535.55 - 120,000 - 0) / (229,535.55 - 0)
The determination of i is done iteratively. If 0.06 is used for i, the result is 0.05064, and if 0.04 is used for i, the result is 0.04915. When 0.05 is used for i, the result is 0.05.
The property interest rate implies all market expectations, such as the future interest rate level, price increases, and increases in value. In our example, the interest rate level is constant (flat yield curve), and the prices and values are constant.
Let's return to the example of the original capitalised earnings method with taxes and growth. Suppose the market property has a value of 480,000 MU, a land value of 240,000 MU (half of the property value), a net income of 12,000 MU (sic!), a residual utilisation period of 50 years, and a property-specific adjustment of 0. (Net income is not adjusted for income taxes.)
i = 12,000 / (480,000 - 0) - [((1 + i)^50 * i) / ((1 + i)^50 - 1)] * (1 + i)^-50 * (480,000 - 240,000 - 0) / (480,000 - 0)
The property interest rate is approximately 0.0189 and implicitly includes all the factors from above.