Definition
Canadian provinces finance their deficits and debt by issuing bonds on financial markets. Quebec issues Quebec Government Bonds (QGB) through Finances Québec, generally at slightly higher rates than federal bonds (Canadian bond of the same term) due to provincial credit risk.
Link to mortgage rates: financial institutions that grant mortgage loans finance part of these loans through bond borrowings. The cost of this financing influences — in part — their offered fixed rates. However, for CMHC-insured mortgages (securitization via Canada Mortgage Bonds), the main reference is the 5-year Canadian federal bond yield.
The Quebec-Canada spread (difference between QGB and GoC rates of the same term) generally fluctuates between 20 and 60 basis points depending on market conditions.