According the Italy 1990 FIFA World Cup technical report,
An assist point can be awarded to a player when he/she:Makes the last pass to the eventual goalscorer Makes a penultimate pass that decisively influenced the play leading up to the goal Attempts a shot on net which rebounds, allowing the goalscorer to successfully score Is fouled (in the attacking half), and the kicktaker scores directly from the kick (unless he/she is taking the free kick themselves)
An assist point cannot be rewarded for :Solo efforts (e.g. dribbling runs) A goal scored as the result of a mistake of the defending team
An update to the definition of an assist was provided in the Mexico 1986 World Cup technical report:In order to get an assist for the goalscorer taking advantage of a shot's rebound, the assister's shot must be on target. Up to two people may receive assist points if their passes were decisive and/or significant
These are all the...