From an
old article but cannot see where these have changed:
According to the NCAA’s rules, if a touchdown is scored as time expires, the period can be extended for a try except if it happens in the fourth period and the points would not affect the outcome of the game.
If you’re really into rules and the NCAA’s definition these are the rules:
RULE 3, SECTION 2 ARTICLE 3.C
Extension of Periods
ARTICLE 3. a. A period shall be extended for an untimed down if one or more of the following occurs during a down in which time expires (A.R. 3-2-3-I-VIII):
…
c. If a touchdown is scored during a down in which time expires, the period is extended for the try (Exception: Rule 8-3-2-a).
RULE 8 SECTION 3 ARTICLE 2.A.
Opportunity to Score
ARTICLE 2. A try is an opportunity for either team to score one or two points while the game clock is stopped after a touchdown. It is a special interval in the game which, for purposes of penalty enforcement only, includes both a down and the “ready’’ period that precedes it.
a. The ball shall be put in play by the team that scored a six-point touchdown. If a touchdown is scored during a down in which time in the fourth period expires, the try shall not be attempted unless the point(s) would affect the outcome of the game.