Malcolm Turnbull has promised to release the Coalition's plans for a national broadband network ''months'' before the September 14 election to allow for scrutiny of the policy and its costings.

The undertaking from the communications spokesman goes further than the usual opposition response to questions on when key election policies will be made public this year - which is to simply say ''in good time''.

''You can never criticise me for not providing a lot of detail,'' Mr Turnbull said in an interview with Fairfax Media's Breaking Politics.

''Australians will have more than adequate time to consider our policy and debate it.''