# Age depreciation

The Age impairment refers to the impairment of a thing during their lifetime or total useful life due to wear , abrasion , consumption or due to aging processes .

Since it is often not possible to precisely determine the actual age depreciation , various approximation methods are used to determine the value .

Depending on the method used, a residual value remains at the end of the service life .

## Procedure

The following terms are used in the formulas below:

• ${\ displaystyle A}$ is the age of the thing
• ${\ displaystyle G}$ is the total useful life or service life
• ${\ displaystyle w}$ is the age depreciation in%

### Linear age depreciation

This method assumes that the value of a thing is 100% present when it is created and then decreases evenly over the course of its life .

${\ displaystyle w = {A \ over G} \ times 100}$ ### Age reduction according to Ross

The procedure was mainly used in the real estate industry for valuations. The consideration that a property has less depreciation in the first few years of its life than in the later has been taken into account in this formula. The Real Estate Valuation Ordinance (ImmoWertV) has been in force in Germany since July 1, 2010. In § 23 ImmoWertV, a linear depreciation is now provided for as a rule.

${\ displaystyle w = {1 \ over 2} \ times \ left ({\ left ({A \ over G} \ right) ^ {2} + {A \ over G}} \ right) \ times 100}$ ### Parabolic depreciation

With this procedure, the age depreciation has a parabolic course.

${\ displaystyle w = \ left ({A \ over G} \ right) ^ {2} \ times 100}$ ### Age reduction according to Vogels

This method is based on empirical studies of purchase prices. At the end of the total period of use, there is still a residual value of 20%.

${\ displaystyle w = \ left ({- 0.4 \ times \ left ({A \ over G} \ right) ^ {2} +1.2 \ times {A \ over G}} \ right) \ times 100 }$ ## Individual evidence

1. Sprengnetter: Review of six months ImmoWertV. (No longer available online.) Archived from the original on July 14, 2014 ; Retrieved June 12, 2014 .