Stamp duty laws in Queensland may hinder the sale of covered bonds by Australia's largest banks, given strict rules that require payment of the tax on the transfer of ownership of mortgages.Different banks are treating the legal difficulty differently.Commonwealth and Westpac have taken a cautious approach and left home loans for borrowers in Queensland out of the covered bond pools established during the last month.National Australia Bank and ANZ are taking a more sanguine view of Queensland's stamp duty laws and have included home loans to customers in that state in the pools. Reports by Fitch Ratings shows that 23 per cent of home loans for NAB's planned debut covered bond are in Queensland. For ANZ the proportion is 12 per cent.No bank has yet sold a covered bond, though marketing to potential investors continues in Europe, and one or more issues are likely before the end of the month.The stamp duty issue may be a technical legal issue with an administrative solution. Administrative rulings from the Office of State Revenue already cater to the transfer of ownership of mortgages to special purpose vehicles that own the home-loan pools behind mortgage-backed securities.However, this administrative measure is specific to mortgage-backed securities and it's not clear how much time the OSR may take to resolve the issue in favour of banks, assuming officials are inclined to do so. (Banking Day was unable to obtain comment from the Office of State Revenue of the Treasurer's Office on the topic.)