What is offside?

Players of the attacking team must not precede the puck into the attacking zone.

• Skates, not sticks, decide offside. A player is offside when both skates are completely over the leading edge of the blue line.
• A player is onside if either skate is in contact with the blue line, or on his own side of it, at the instant the puck completely crosses the leading edge of the blue line.
• A player controlling the puck who crosses the line ahead of it is not offside, as long as he had possession and control of the puck with his stick before his trailing skate completely crossed the blue line, and he keeps possession and control immediately after the puck enters the zone.
• A puck propelled by the attacking team that deflects off any player is ruled offside or delayed offside, as appropriate.
• If a player legally carries, passes or plays the puck back into his own defending zone while an opposing player is in that zone, the offside is ignored and play continues.

Source: NHL Official Rules 2026-2027, Rule 83.