Offsetting or not?
 

Offensive guard is lined up in the neutral zone, which is a life ball foul. Defensive nose guard encroaches just before the snap. Whistle and flag, but What do we have?

Rule set?

No it's not. In both NCAA and Fed, it may not be called right away but it is a foul for a Team A player to enter the neutral zone as soon as the neutral zone is established.

A true live ball foul, such as illegal formation, is not a foul until the ball is snapped. If there is a dead ball foul before the snap, the live ball "foul" never actually happened and the dead ball foul is enforced.

If you talking Fed, the encroachment by A's guard is the first and only foul as it is a dead ball foul when he lined up in the NZ. Whatever B player did after doesn't matter, unless he committed a personal foul.

What if he had never been on his side of the neutral zone since the ball was made RFP?

Did you read these two posts?

Your question has nothing to do with this play. The play is about a player who is LINED UP in the neutral zone. Is your player lined up in the neural zone? No.

Actually in the case I had in mind, he is. Team A is going with no huddle, and he lined up there before the RFP and never got onside. Then the snapper puts a hand on the ball and the rest of the team lines up, and then a player from B enters the neutral zone. I honestly wouldn't know how to rule there.

As soon as the snapper puts his hand on the ball, the restrictions go into effect. In this case, it's a dead ball foul on the offense.

A fouled first - Dead ball foul !!

There are allowances for entering substitutes who may run onto the field, (across/through the NZ even) after the RFP and after center touching ball. If they do not get onside before ball is snapped then we would have an Ill sub foul. (sorry don't have rules books a with me for a ref.).
If while a sub is running onto the field (on B's side of the LOS, lets say) and B encroaches, I am thinking by rule we have encroachment on B. However, by fairness and common sense I would think about offsetting them...until I find my rule/case book that may instruct me otherwise .

I think it best to stick with the original post.

We can "what if" a play thread to death.

Point taken HL...I generally agree with staying away form the what if's, yet sometimes going a little deeper and describing a similar play or a play related to the question on thr OP may add some insight and a better learning opportunity about extending the application of the rule...:)

As a 2nd year football guy, I agree. Discussing the sasquatches sometimes helps to understand the basics.

Especially what the what-if plays actually happen, such this interception in the 2001 Peach Bowl...

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I think what ifs are great learning tools for really understanding the finer points of the rules.

Actually when I read the original post, I thought he meant it my way. Any other way, the answer looked too obvious, so that's why I thought he was asking.