The Guaranteed Starters
From 2005 through 2012 NASCAR guaranteed the top 35 teams in car owner points a spot in the starting lineup. That rule was abandoned for the 2013 season. NASCAR returned to the pre-2005 rules where the top thirty-six positions are determined by speed.
If you are one of the fastest drivers during qualifying then you will start the race regardless of how many points you have.
After the top 36 spots are set by speed NASCAR reserves a few positions for drivers who have a problem during their qualifying run. This allows a top team to have a crash or equipment failure during qualifying and still make the race.
The next six positions (37-42) are set by car owner points for teams that didn't make the race based on qualifying time. These teams line up based on points and not speed.
This leaves one final spot which is known as "The Champions Provisional." This final 43rd starting position is reserved for any former NASCAR Champion that didn't qualify for the race any other way (by points or on time.)
A driver can only use the past champions provisional once every six races. If a drivers uses it then they will have to attempt to qualify six more times before they can use it again.
If there is no driver eligible for the Champions Provisional then that spot goes to the eighth fastest driver that is not guaranteed a starting spot based on points.
Some Exceptions To The Rules
The most obvious exception to all of this is the Daytona 500. The Daytona 500 follows its own qualifying process that is unlike any other race on the NASCAR schedule.
Another exception has to do with the all-important car owner points. Through the first three races of the year NASCAR uses the car owner points from the previous season. Beginning with the fourth race of the year NASCAR switches to the current season's car owner points to determine the guaranteed starters.
And finally, what does NASCAR do when it rains or snows or for any other reason qualifying is cancelled? If qualifying is rained out the starting lineup will be determined by practice speeds.
If practice was rained out too then NASCAR lines up the top 42 drivers by car owner points. Then the Champions provisional is still available to a former Champion not in the top 42. If there isn't an unqualified past Champion then the next driver in points gets the last starting spot.
Clear As Mud
NASCAR's qualifying rules can seem quite complex but when you break it down and look at each piece of the puzzle it becomes much more obvious how it all fits together to create the starting lineup for each week's race.