Treasury has changed its rules for identifying fiscal risks.
The move follows a ministerial inquiry which found that a $1.5 billion funding shortfall in ACC's non-earner's account should have been disclosed as a fiscal risk before the last election.
Treasury Deputy Secretary Peter Bushnell says fiscal risks have previously been focussed on policy decisions the Government had not yet taken.
He says the new rules include all circumstances likely to have a material effect on the fiscal and economic outlook.
Dr Bushnell says under a subjective new rule of thumb, matters with greater than 50% likelihood will make it into the Budget forecasts.
Those with more than a 20% possibility will be considered for inclusion as fiscal risks.