The drug or medicine Xanax stays in most peoples urine for 5 to 7 days before it clears out of your urine entirely.
Usually after 4 days the Xanax cannot be detected in a persons urine and won't show up in a drug test.
For most users they have the Xanax out of their systems and urine within 4 days although some people may still have it in their system for 5 to 7 days.
So I would recommend not taking the Xanax if possible 7 days before a drug test is to occur to make sure that you don't have any Xanax in your system.
Although if you can show an employer or whoever is having the drug test done that you have a prescription for and are taking the drug Xanax because it's needed then most times you can still get a job even if the drug test detects the Xanax or other prescription drug in your system.