It depends on exactly what the LA say is their policy. The cut off date for on time applications is the 31st October. However most LAs have a short period after this, when parents can change address and their new address can be used and treated as an on-time application. Typically this is 4 to 6 weeks period. After that cut off date, you are obliged to inform the LA that you have moved, but if you ask them to change address for admission purposes then you will be classed as a late application and effectively go to the end of the queue for places as all on-time applications are dealt with first. Given what you have said, the best option is to inform the LA when you move, so it is does not create any issues over trying to deceive the council over where you are living. However tell them to take the new address for communication purposes only. That means that the LA will continue to use the original address for admission purposes and from what you have said you will probably still get your preferences. It is all about dates, so you need to make sure that you have the relevant dates, which will be on the LA website and in the actual booklet produced by the LA.