There are some appropriate reasons to ask for a time extension. For example, if you have an interview lined up for another job already, you can ask for time to perform the interview and await for the decision for that job. Another reason you can ask for an extension is when accepting this job offer requires relocation. This can be a tough decision, especially when you have a family who will be relocated as well. If you are currently employed, you may need time to transition out of your current position smoothly. This is a good reason for an extension, as it shows your professionalism to your current employers, and that will be noticed by your future employers