When should I complete and pay a form11 return?

I have received conflicting information please clarify for me.
Using ROS form11, I believe for 2008 I complete a return/pay in Oct. 2008.
For 2009 I complete/pay a return in Oct. 09 plus the balance of 2008.
I assume ROS adds on the 2008 balance to my 2009 return for total payment.
Is this correct?

If you correctly complete and file a 2008 Form 11 and have sufficient Preliminary Tax paid then the balance of 2008 is due 31/10/09 ( or such extended date in November as Revenue dictate, usually around the 17th for filing and payment on ROS) . When you file the Form 11 you can complete a Pay & File payment notice to pay (a) your balance of 2008 Income Tax and (b) your Preliminary 2009 Income Tax.These two will be added together and paid in October/November using the Ros Debit Instruction at the date you specify but not later than the return filing deadline.

Thanks Graham, that's precise.