An athlete can be disqualified in the following ways:

Impeding: Deliberately blocking, charging, impeding, or pushing another competitor

Two false starts: Starting before the gun sounds to start the race. Each competitor is allowed one false start, and is disqualified after a second.

Off-track: Skating inside the turn markers

Slowing down: Slowing down unnecessarily 

Team skating: In which skaters conspire to affect the outcome of the race

Kicking out: Deliberately kicking out a skate and endangering another skater anywhere in the race; also throwing oneself across the finish line is forbidden

If a competitor infringes the racing rules in a manner deemed unsafe, harmful or hazardous by the referee, a yellow card will be shown to the infringing skater.  The skater will be disqualified from that race and excluded from the remainder of that event's competition. The skater will forfeit results accrued in the previous rounds of that event.

If the infringement occurred in a relay, than the team faces the same sanction.

In the case of an infringement of the rules, which is deemed by the referee to be intentionally dangerous or grossly negligent, the skater will be shown a red card. In the case where a skater is shown two yellow cards in the same competition, the skater also will be shown a red card. 

For any improper conduct, either on or off the ice, a red card may also be shown to the skater.

A skater who is shown a red card will be excluded immediately from the particular distance as well as the rest of the Olympic Winter Games, and will be listed on the bottom of the event classification with no rank. If a skater is shown a red card in a relay race, the affected relay team will be immediately excluded from the relay competition, and will not be ranked in the relay classification. Individual sanctions for the skater(s) concerned will also apply.

Sanctions are not retroactive. A skater being shown a red card, for instance, in the last distance (1000m), will not have his/her previous results over the other distances (500m and 1500m) deleted.

Disqualifications are called after the race concludes. When there is a violation, or if someone takes out another athlete in a fall, the victim of the infraction may be allowed to advance, providing he was in contention to advance otherwise; advancement is the discretion of the chief referee. When athletes are allowed to advance, it is possible to have a heat – or even a final – with more than the usual four skaters. 

Once a skater is eliminated in the heats or quarterfinal, he/she is finished. There is no repechage. Each event has an A final and a B final. The A final determines the medalists. The B final, or consolation final, determines placement. However, it is possible for a B finalist to earn a medal if, for example, only two athletes complete the A final without disqualification. They would receive gold and silver, and the top finalist in the B final would receive bronze.

If a skater qualifies for an individual final and is injured before it is contested, he or she is not replaced.