see also https://sagecity.na.sage.com/support_communities/sage_50_accounting_ca/sage50ca-yearend/

The Sage 50 software is designed to work with a maximum of two open fiscal years.  (and they have to be the two most recent years).

For example, if you open a year that ends in 2016, you will still be able to configure Sage 50 Canadian (under Setup | Settings | Company | System) to allow accounting entries into the previous fiscal year ending in 2015, and you will no longer be able to enter anything into fiscal years prior to 2015.  (even if they are part years).

Payroll is a bit different, if you use payroll you should be aware of the effects of opening a new Calendar year.   If you don't use payroll, there's nothing for opening the new calendar year to affect.

see also https://sagecity.na.sage.com/support_communities/sage_50_accounting_ca/sage50ca-yearend/

The Sage 50 software is designed to work with a maximum of two open fiscal years.  (and they have to be the two most recent years).

For example, if you open a year that ends in 2016, you will still be able to configure Sage 50 Canadian (under Setup | Settings | Company | System) to allow accounting entries into the previous fiscal year ending in 2015, and you will no longer be able to enter anything into fiscal years prior to 2015.  (even if they are part years).

Payroll is a bit different, if you use payroll you should be aware of the effects of opening a new Calendar year.   If you don't use payroll, there's nothing for opening the new calendar year to affect.