For your next lot of payments, you can go to the post office and get a payment book, this will allow you to put money towards your rego throughout the year so it isn't such a bit payment when it comes time to paying it next time around.

Qld do 6 months of rego for all vehicles, the option is on your bill, which didn't come a few weeks before it is due I might add, they are sent out 6 weeks before your rego due date.

If you don't pay by the date, then you will get hit with an extra amount to pay.

They probably won't give you extensions.
I wonder if all states do that with th PO?

Ours is due June 30th but hasn't come yet.
The right govt dept might send them out but it doesn't mean Aus post gets them to you