When trying to roll over an error appears saying you have not finalised your BAS returns (even when you have), it may be because you have not included PAYG in your finalised returns.
NOTE: This solution is only for companies that do NOT use payroll and hence do not need to report PAYG amounts in BAS.
If you do not use the Payroll component of Cashbook (i.e. do not pay PAYG Withholding Tax)
You should then be able to roll over successfully.