O.K. i am after some answers here which i couldnt find at vicroads or the search function.
I am looking at a set of personalised number plates second hand and dont have the car finished that they will go on , do i have to put them on a car to hold them or is there a set time that they can be off a car before they re-enter the system . I dont really want to put this plates on my ef ford just to hold on to them . Any one know ? thanks in advance

G'day, you don't have to have them on a car, to hold on to them, you can just put them aside.
in some states you have an anual cost but in QLD you just buy them outright, atleast for now.

i know is S.A. there is a few type of personal plates 1 you pay once thats it 2 you pay every year and if you dont renew after 3 years the plates go back in the system and any one could get them then
it all depends on which state and what plates you have

If they are Vic plates and have been put in your name, you can hold them for as long as you like. All you will have to do when fitting to car is go to Vic Roads and pay the $80 to register to your car.
if you bought the plates new, that $80 is factored into the price.

I bought new plates that sat in my garage for just over a year before fitting to the car.

If you're buying secondhand, fill in the plate transfer form signed by the previous owner. You need to keep the plates and the signed form with you 'till you are ready to fit them to your car. When ready take both to Vicroads and pay the fees to fit. Done.

There used to be a loop hole where after 12 months someone "could" apply for the same plates if they weren't fitted by the original purchaser to a vihicle and rego'd. But that was closed after a couple of cars were registered with the same plates and appeared on ACA and Today Tonight a few years back.