What Is It?
In many countries, you are able to deduct the cost of purchasing and rehabbing a property on your income tax return.
Rather than claiming the entire deduction in the year you purchase the property, you are typically required to distribute it over the course of the property's "useful" life span (the depreciation period).
For example, in the United States, the useful life span of most residential properties is typically 27.5 years, while the useful life span of most commercial properties is typically 39 years.
If you do not reside in the US, check your local tax laws for the applicable depreciation deduction rules.