According to the Bank of Canada, individual financial institutions set their own prime rates, which are determined by competitive pressures between the financial institutions and the cost of short-term funds. Thus, the prime rates of financial institutions can change at any time.
The Bank of Canada, however, influences the cost of short-term funds and the prime rates by raising or lowering the key policy rate, which is the rate at which major financial institutions borrow and lend funds among themselves.
In December 2000, the Bank of Canada began using a system whereby it announces eight times per year whether or not the key policy rate is changing. The dates on which these announcements are made are set and published in advance. The schedule for Key Policy Rate announcements for 2015 and 2016 are located at the Bank of Canada website.