How can I see the RFC associated with the e.firma/FIEL that I have?

Checking the information of your e.firma such as the associated RFC is very easy from your computer

You can visualize the RFC (tax ID) associated with your FIEL from your computer. This way, if you handle more than one e.firma (your individual one and one or more from legal entities where you are their legal representative), you will be able to know which one belongs to what person or entity.


  1. Process in Mac
  2. Process in Windows

Process in Mac

  1. Open Finder.
  2. Find your e.firma files.
  3. Click once on the .cer file.
  4. Press the spacebar on your keyboard. A small window will open, there you will be able to visualize your e.firma information.
  5. In the “Name of the subject” section, the “Unique identifier” is the RFC associated with that e.firma.
  6. Press the spacebar on your keyboard to exit the visualization window.

Process in Windows

  1. Open the file explorer.
  2. Find your e.firma files.
  3. Double-click on the .cer file.
  4. Click “Open”. From now on, try not to modify anything since it could corrupt the file.
  5. Click the “Details” tab.
  6. In the table, look for “Subject” and click it once.
  7. In the visualization screen under the table, you will find the RFC. It’s the second on the list next to a number sequence and the “=” symbol.
  8. Press the “x” on the top right corner of the screen to exit.