The method of calculating a security deposit deduction for repair or replacement of an item in a rental home prorates the total cost of the repair or replacement such that the resident pays only an amount relative to the remaining useful life of the item that the resident has damaged. For example, suppose a resident has damaged an eight-year-old carpet that had a life expectancy of ten years, and that a replacement carpet of similar quality would cost $1,000. We could properly charge only $200 for the two years’ worth of life (use) that would have remained if the resident had not damaged the carpet. All fixtures, appliances, furnishings, etc. in a home have a defined useful life.