The length of time transactions are kept in Infusion depends on the following settings:
Admin \ Defaults \ Manage Customer Defaults
Admin \ Defaults \ Manage Supplier Defaults
Admin \ Defaults \ Manage Product Defaults
In the above example, transactions will be available for 7 years following the end of year roll over.
This can increase the number of years, but this may slow down the system depending on the number of transactions in retained in the system.
This is why you are prompted to run an end of year back up.
Inland Revenue Department IRD requires you to keep your records for seven years.