Are you talking about for a CDL driver, or no? For a CDL driver operating a CMV, you must be at least 18 to drive intrastate, and at least 21 to drive interstate.
You need to go to the DMV and identify as an interstate driver (which you should have done, even if you were driving intrastate at the time). If you were restricted to intrastate only due to age concerns, you need to get a duplicate from the DMV with the age restriction removed.
18 with an intrastate only restriction, 21 for interstate use or anything requiring a hazmat endorsement.
If you don't need a CDL operating that vehicle intrastate, you don't need it to operate that vehicle interstate, either.
You can get an intrastate-only CDL at the age of 18. To drive interstate, you must be 21.
You must be 18 for intrastate work, 21 for interstate commerce cartage and to receive a hazardous materials endorsement.
Under federal law, 18, with an intrastate only restriction. 21 to drive interstate and/or get a hazmat endorsement. Some states won't allow anyone under 21 to have a CDL, though.
It means they stay within a single state. Even if someone if renewing or getting their CDL with the intent of only partaking in intrastate transport, they should still self-identify as "non-exempted interstate".
interstate - or within a state; intrastate is between states.
for Texas its 18 but only for intrastate driving, 21 for interstate driving, intrastate meaning inside the state only interstate meaning from state to state.
If they are in the same state, it is intrastate. If they are in separate states, it is called interstate. Since Brisbane and Sydney are in different states, the answer to your question is "interstate".
Interstates go out of state, and intrastates stay in.