The depreciation calculation method is the most important characteristic of the internal calculation key. The calculation method enables the system to carry out the various types of depreciation calculation. Depending on how the calculation method is set up, the system determines which further control parameters need to be specified and which do not need to be specified. The following depreciation calculation methods are possible:

There are two versions of this method. In the first, the system determines a depreciation percentage rate from the total useful life; the rate remains the same for each year. The second version calculates a new percentage rate for each year based on the remaining useful life. In this version, the depreciation percentage rate rises constantly and then reaches 100% in the last year of the useful life.

This method allows you to depreciate a certain percentage rate from the depreciation base within a tax concession period. In order to calculate the current periodic depreciation, the system first determines the accumulated depreciation up to the period under examination. The period depreciation is the difference between the already existing depreciation and the total depreciation allowed. With subsequent acquisitions, the system automatically catches up depreciation from previous years in a lump sum.

In contrast with the total percentage rate, here you specify the percentage rate for each fiscal year. The system uses this percentage rate for calculating depreciation for each period. For example, you can depreciate 3.5% in each of the first 12 years, then 2% a year for 20 years and 1% per year for the remaining 18 years. The total of the percentage rates over the useful life is logically always 100%, so that complete depreciation is reached by the end of the useful life.

This method is used as a changeover method following depreciation within the tax concession period of an investment support measure. The net book value of the asset will be depreciated over the total useful life when the tax concession period ends (that is, the actual duration of depreciation encompasses the tax concession period plus the total useful life that is entered).

When defining the depreciation areas, you can establish dependencies between them by specifying a mathematical formula. Method "M" allows you to calculate the depreciation in one area from the depreciation in another area using this formula. Using this method you can, for example, calculate the mean value from straight-line depreciation and declining balance depreciation.

Unit-of-production depreciation is based on the output-related use of the asset. When you specify a total expected output or a total expected number of units, and the exact output per period or exact unit of production output figure per period, the system determines the resulting depreciation for each period. You maintain these production figures at the level of the depreciation key. For this type of depreciation, therefore, you generally need only an internal calculation key in which the unit-of-production method of depreciation is specified.

In the same way as with the unit-of-production method of depreciation, the amount of depreciation here is dependent on output. In contrast to the unit-of-production method of depreciation, the system uses the remaining units of production and not the total units of production to determine the periodic depreciation. Depreciating using the remaining units of production ensures that, for post-capitalization, the book value reaches zero when the total output or the total units of production is reached.

An arithmetic sequence is set up based on the total useful life. The depreciation percentage rate is proportional to the remaining useful life.