American Football Rules IFAF Approved Ruling 10-2-5:IX-XI

IX. Team A fouls after it scores a touchdown, and Team B fouls after a successful try. RULING: Allow the score. Team B has the option of Team A being penalised on the try, the succeeding kickoff, or from the succeeding spot in extra periods. For the foul after the try, Team B is penalised on the kickoff or at the succeeding spot in extra periods. [Cited by 10-1-7, 8-3-3-b-1] Fouls during a try with no change of team possession (this does not include live-ball fouls treated as dead-ball fouls or loss-of-down fouls):
X. Team B fouls during a successful try. RULING: Repeat the down after enforcement, or the penalty is declined by rule. Penalties for personal fouls and unsportsmanlike conduct fouls may be enforced on the succeeding kickoff or at the succeeding spot in extra periods (Rule 8-3-3-b-1). [Cited by 10-1-7, 8-3-1, 8-3-3-b-1]
XI. Team B fouls during a successful try. RULING: Repeat the down after enforcement or the penalty is declined by rule. Penalties for personal fouls may be enforced on the succeeding kickoff or at the succeeding spot in extra periods (Rule 8-3-3-b-1). [Cited by 10-1-7, 8-3-1, 8-3-3-b-1]