Txtag / HOV lane

Hey, Newbie question as we just moved from abroad and got my Txtag.

​

How does it work when a lane is Toll/HOV 2+.

​

If you go to Toll road having a tag, but you actually have 2 or 3 passengers in the car? will you still be charged? does the system have a way to know not to charge you?

​

Thanks!