NASCAR owns and assigns all numbers to car owners while reserving the right to revoke or transfer any number at any time.
Car owners cannot assign or transfer a number. Teams can request specific numbers, however, and NASCAR works with teams and sponsors to try and meet those requests, when able.
The numbers NASCAR doles out are good for one year via an owners’ license; generally, teams are re-issued the same numbers from year to year, if requested.
If multiple teams request the same number, the team submitting the first entry form would generally have their request granted, although full-time racing status may also be considered.