Permanent staff change to contract staff with commencing date back dated

Recently my company wanted to change all permanent staff to contract staff. Reason given was to give more benefits to us. The benefit was just adding 2 more days of annual leave. They offer us 1 year of contract but commencing from 1st January 2017, instead of 1st June/July 2017. Can they back date the contract? Can they just do this? This is like terminate us and then offer us a contract. Shouldn't they need to give us notice or salary in lieu because this is consider as termination? Can I choose not to sign and still being permanent?

Can I choose not to sign and still being permanent?

Can.

The Company cannot unilaterally change you from being permanent staff into contract staff. It is a breach of a fundamental term of the contract. Under no circumstances should you accept such an offer to convert to contract staff. Put your foot and state that your not accepting. If they terminate you, file an unlawful dismissal claim at the nearest Industrial Relations Department within 60 days from your last date of employment. You will have a clear cut case to win.