The Reserve Bank of New Zealand has released more details of its planned 'speed limit' for low deposit mortgages, but it has yet to pull the trigger on the controversial policy, which is designed to reduce the risks to the banking system of a property bust.On Tuesday, the bank released its response to the submissions on its June proposal for a limit on the growth of high loan-to-value ratio mortgages granted by banks. It again rejected government moves to exempt first-home buyers, but it also said banks would, initially, be given more time to slow the momentum of their high LVR lending if the trigger was pulled. The Government announced an expansion of first-home buyer subsidies on Sunday in an attempt to soften the effect on these buyers of the speed limit.The central bank gave no time-frame for the final go-ahead for the policy, but economists said the policy was likely to be introduced by the end of the year and it could be as early as September.The bank's response included few major changes from its initial proposal. It continues to exempt government guaranteed mortgages, bridging loans and loans to those moving home and not increasing their loan amount.However, Reserve Bank deputy governor Grant Spencer said some banks had indicated they might be unable to meet the high LVR restrictions in the first few months because they already have a pipeline of loans that are pre-approved for up to six months."To address this issue, we have decided that banks would initially be required to meet a speed limit on high LVR lending measured as an average rate over a six-month window," Spencer said.After this initial six-month window, banks with lending of over NZ$100 million a month would have to abide by a speed limit with a three-month window, as originally proposed. The central bank also said the speed limit would only apply to the New Zealand balance sheets of branches of overseas banks, although the local registered branch would not be able to help other parts of the bank overseas to write high LVR loans.  The Big Four New Zealand banks, which are owned by CBA, NAB, ANZ and Westpac, are fully registered as New Zealand banks, rather than as branches.Spencer warned that if the speed limits were implemented bank staff and directors would be expected to follow the spirit and not just the letter of the policy."In particular, they will need to ensure that the policy is not avoided or undermined through innovative lending practices," he said.Some commentators have warned that finance companies could be set up to circumvent the rules or that banks would create vehicles or practices to avoid the speed limits.The central bank repeated that it would announce the restrictions two weeks before they take effect. It said it had received 10 submissions from banks and had sought more information from them on their stocks of high LVR mortgages and pre-approvals."The data confirmed that some banks could potentially breach an LVR restriction, even if they were