American Football Rules IFAF Approved Ruling 3-2-3:VI-VII
VI. Team A scores a touchdown during a down in which time expires. During Team A’s successful try, Team B fouls. RULING: The period is not extended for the kickoff. Team A may accept the penalty and repeat the try, or decline the penalty and accept the score. Penalties for personal fouls and unsportsmanlike conduct are enforced on the subsequent kickoff or the succeeding spot in extra periods. [Cited by 10-2-5-e, 3-2-3-a, 8-3-3-b-1]
VII. Team A scores a touchdown during a down in which time expires. After the try ends, either team commits a dead-ball foul. RULING: The try may be repeated for an accepted penalty if a live-ball foul occurred during the try; the penalty for the dead-ball foul will then also be enforced on the repeated try. The period is not extended to enforce a penalty for a dead-ball foul. If accepted, this penalty must be enforced on the kickoff to start the next period or at the succeeding spot in extra periods [Cited by 10-2-5-e, 3-2-3-a, 8-3-3-d-2, 8-3-5]