Eligible receiver In American football and Canadian football , not all players on offense are entitled to receive a forward pass . Only an eligible pass receiver may legally catch a forward pass , and only an eligible receiver may advance beyond the neutral zone if a forward pass which crosses the neutral zone is thrown . If the pass is received by a non - eligible receiver , the penalty for the foul " illegal touching " is assessed ( the play is treated as an incomplete pass , unless the ball is downed behind the line of scrimmage — in either case a down is lost ) . If an ineligible receiver is beyond the neutral zone when a forward pass which crosses the neutral zone is thrown , a foul of " ineligible receiver downfield " ( penalty — a loss of yardage , but not loss of down ) is called . Each league has slightly different rules regarding who is and is not considered an eligible receiver . College football . The NCAA rulebook defines eligible receivers for college football in Rule 7 , Section 3 , Article 3 . The determining factors are the player ' s position on the field at the snap and their jersey number . Specifically , any players on offense wearing numbers between 50 and 79 are always ineligible . All defensive players are eligible receivers and offensive players who are not wearing an ineligible number are eligible receivers if they meet one of the following three criteria : Players may only wear eligible numbers at an ineligible position when it is obvious that a punt or field goal is to be attempted . A receiver loses his eligibility by leaving the field of play unless he was forced out by a defensive player and immediately attempts to get back inbounds ( Rule 7 - 3 - 4 ) . All players on the field become eligible as soon as the ball is touched by a defensive player or an official during play ( Rule 7 - 3 - 5 ) . Professional football . In both American and Canadian professional football , every player on the defensive team is considered eligible . The offensive team must have at least seven players lined up on the line of scrimmage . Of the players on the line of scrimmage , only the two players on the ends of the line of scrimmage are eligible receivers . The four remaining players in the backfield ( five in Canadian football ) , including the quarterback , are also eligible receivers — except in the National Football League , where a quarterback who takes the snap from " under center " is never eligible , but is nonetheless not counted toward the seven men required on the line of scrimmage . If , for example , eight men line up on the line of scrimmage , the team loses an eligible receiver . This can often happen when a flanker or slot receiver , who is supposed to line up behind the line of scrimmage , instead lines up on the line of scrimmage between the offensive line and a split end . In most cases where a pass is caught by an ineligible receiver , it is usually because the quarterback was under pressure and threw it to an offensive lineman out of desperation . In many leagues eligible receivers must wear certain uniform number s , so that the officials can more easily distinguish between eligible and ineligible receivers . In the NFL running backs must wear numbers 20 to 49 , tight ends must wear numbers 80 to 89 ( or 40 to 49 if the numbers 80 to 89 have been exhausted ) , and wide receivers must wear numbers 10 to 19 or 80 to 89 . In the CFL ineligible receivers must wear numbers 50 to 69 ; all other numbers ( including 0 and 00 ) may be worn by eligible receivers . A player who is not wearing a number that corresponds to an eligible receiver is ineligible even if he lines up in an eligible position . However , a player who reports to the referee that he intends to be eligible in the following play is allowed to line up and act as an eligible receiver . An example of this was a 1985 NFL game in which William Perry , wearing number 72 and normally a defensive lineman , was made an eligible receiver on an offensive play , and successfully caught a touchdown pass attempt . A more recent example , and more commonly used , has been former New England Patriots linebacker Mike Vrabel lining up as a tight end in goal line situations . Before the snap of the ball , in the American game , backfield players may only move parallel to the line of scrimmage , only one back may be in motion at any given time , and if forward motion has occurred , the back must be still for a full second before the snap . The receiver may be in motion laterally or away from the line of scrimmage at the snap . A breach of this rule results in a penalty for illegal procedure ( five yards ) . However , in the Canadian game , eligible receivers may move in any direction before the snap , any number may be in motion at any one time , and there is no need to be motionless before the snap . The rules on eligible receivers only apply to forward passes . However , any player may legally catch a backwards or lateral pass . In the American game , once the play has started , eligible receivers can become ineligible depending on how the play develops . Any eligible receiver that goes out of bounds is no longer an eligible receiver and cannot receive a forward pass , unless that player re - establishes by taking three steps in bounds . Also , if a pass is touched by any eligible receiver ( tipped by a defensive lineman , slips through a receiver ' s hands , etc . ) , every offensive player immediately becomes eligible . In the CFL all players become eligible receivers if a pass is touched by a member of the defensive team . High school . In high school football , the rules of eligibility are roughly the same as in the college game . However , as of February 2009 , at least four players must wear numbers between 50 and 79 on first , second , or third down , which by rule would make them ineligible receivers . This was because of a change in the definition of a scrimmage - kick formation made by the National Federation of State High School Associations ( NFHS ) . The change was intended to close a loophole in the rules which allowed teams to run an A - 11 offense , in which a team could legally be exempted from eligibility numbering restrictions if the player receiving the snap was at least seven yards behind the line of scrimmage .