The security deposit interest rate has been 0% since 2009, meaning that for any tenancy ending in 2012 that began later than January 1, 2009, there is no interest payable.
Interest rates for earlier years were 1.5% for each of 2007 and 2008, 0.5% for 2006 and 0% for 2002 to 2005 inclusive.
Security and pet damage deposit interest is compounded, so when a tenancy of many years' duration ends, an appreciable amount of interest might be due to the departing renters. You can calculate the amount of interest owing in literally a few seconds by using the Residential Tenancy Branch Deposit Interest Calculator. Go to rto.gov.bc.ca and click on Deposit Interest Rates & Calculator in the column on the left of the page.
-- Al Kemp