Interception by B for a touchdown...
 

I did not call for the last few years and they have changed the rule concerning penalty enforcement after a touchdown. I have read all the case findings if A scores and B fouls.
If B intercepts A's forward pass and runs for a touchdown but before crossing the line A is guilty of face mask at the 5 yard line does the peanlty carry over to the try or the next kickoff?

NF: 8-2-3: When opponent of scoring team fouls (other than a succeeding spot foul) during the down in which a TD is scored, and there WAS a change of possession, And the Foul occurs after the occur AFTER the change of possession, the scoring team can choose to enforce the penalty: (a.) On the Try, or: (b.) On the subsequent KO.

Or in understandable English, A fouls after change of possession and then B scores without further change of possession, B gets the choice of enforce on the try or on the KO.

Thanks--


Is there any situation where a touchdown is scored and the opponents commit the only live ball foul (other than end of 4th quarter) where the option of taking penalty on subsequent kick off is not given?

If the foul comes before a change of possession, the scoring team doesn't have the option.

Example: A85 commits offensive pass interference but B26 still intercepts the ball and returns for a touchdown. Because the foul occurred before the interception, this does not qualify under any of the special circumstances in 8-2. Thus B would have to decline A's penalty in order to accept the results of the play.

That's just the first situation that comes to mind. There are probably others.

The thing to remember is that there are 3 situations where the live-ball penalty on a TD can be enforced on the ensuing kick:
1) B fouls on a play where there is no change of possession (8-2-2)
2) The non-scoring team fouls on a play where there is a change of possession AND the foul occurs after the change of possession (8-2-3)
3) EITHER team commits an unsportsmanlike or nonplayer foul during the play (8-2-4)

Additionally, any dead-ball foul which occurs after the score and up to the ready-for-play has the same penalty option for the offended team. (8-2-5)

And, as always, a foul by B on a successful try gives A the option to take the penalty on the kick. (8-3-5)