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Annual Percentage Rate Calculation Program for Windows (APRWIN)

The Windows-based version of the Annual Percentage Rate program (APRWIN v6.2 - Released May 2008) is an efficient tool for verifying annual percentage rates and reimbursement adjustments. This version includes relevant finance charge and APR tolerances for verifying the accuracy of annual percentage rates and finance charges on loans secured by real estate or a dwelling.

The APRWIN program is only available for download.

For questions about the APRWIN application, please provide a detailed description of the issue, your operating system, your name and a contact number via e-mail to

You can also provide comments and feedback to the address below:

Office of the Comptroller of the Currency
Compliance Policy
Mail Stop 6-6
Washington, D.C. 20219

Although great care has been taken in the preparation of this APRWIN program, the OCC makes no warranty of complete accuracy. Further, the OCC does not recommend this program over other methods to calculate annual percentage rate.

The APRWIN installation will automatically uninstall any earlier version of the APRWIN program from your computer. If you have APRWIN Version 5.0 and would like to keep this version, please follow the steps below before installing this new version.

  1. In Windows Explorer, go to the folder where you placed APRWIN, the default location is C:\APRWIN.
  2. Copy the entire APRWIN folder and paste it into another directory on your C: drive.
  3. Run the 5.0 version from the new directory location.

Download the Program

To download APRWIN to your machine, follow the instructions below. (Note: The file size is approximately 4MB.)

  1. Download one compressed file ( to a temporary folder on your hard drive.
  2. Execute aprwin-software-exe.exe to begin the installation program.
  3. Follow the prompts.

Please note that the APRWIN application is not currently supported on Windows Vista.