Depreciation is a  noncash expense that reduces the value of an asset as a result of wear and tear, age, or obsolescence. Most assets lose their value over time (in other words, they depreciate), and must be replaced once the end of their useful life is reached. There are several accounting methods that are used in order to write off an asset's depreciation cost over the period of its useful life. Because it is a non-cash expense, depreciation lowers the company's reported earnings while increasing free cash flow.

Depreciation is used in accounting to try to match the expense of an asset to the income that the asset helps the company earn. For example, if a company buys a piece of equipment for $1 million and expects it to have a useful life of 10 years, it will be depreciated over 10 years. Every accounting year, the company will expense $100,000 (assuming straight-line depreciation), which will be matched with the money that the equipment helps to make each year.

In Oracle, you can run depreciation to process all assets in a book for a period. If you have assets that have not depreciated successfully, these assets are listed in the log file created by Oracle Assets when you run depreciation.

Closing a Depreciation Period
When you run depreciation, Oracle Assets gives you the option of closing the current period if you check the Close Period check box on the Run Depreciation window. If all of your assets depreciate successfully, Oracle Assets automatically closes the period and opens the next period for the book. If you do not check the Close Period
check box when you run depreciation, Oracle Assets does not close the period.

Once depreciation has been processed for an asset in the current open period, you cannot perform any transactions on those assets unless depreciation is rolled back or the current period is closed

Multiple Reporting Currencies
If you are using Multiple Reporting Currencies (MRC), you can only run the Calculate Gains and Losses and depreciation programs using the standard Fixed Assets or MRC primary responsibility. You cannot run these programs using an MRC reporting responsibility. When you run the Calculate Gains and Losses and depreciation
programs using the standard Fixed Assets or MRC primary responsibility, these program will also run automatically for the associated reporting responsibilities.

To run depreciation:
1. Open the Run Depreciation window.
2. Choose the Book for which you want to run depreciation.
3. Choose whether you want Oracle Assets to close the period after successfully depreciating all assets.
4. Choose Run to submit concurrent requests to run the calculate gains and losses, depreciation, and reporting programs.
Attention: You cannot enter transactions for the book while depreciation is running.
Oracle Assets automatically runs the Journal Entry Reserve Ledger report when you run the depreciation program for a corporate book, and the Tax Reserve Ledger report for a tax book, so you can review the depreciation calculated. These reports are run automatically for the primary currency only. You can use the Standard Report Submission (SRS) process to manually run these reports for the reporting currencies.
5. Review the log files and report after the request completes.
6. If the log file lists assets that did not depreciate successfully, correct the errors and re–run depreciation.