The cost of the JobKeeper wage subsidy will increase by more than $15 billion due to the hammer blow to business caused by the Victorian coronavirus crisis.

Changes to JobKeeper were approved by federal cabinet's Expenditure Review Committee hours after the nation's economic recovery was hit again on Thursday with Treasury forecasting the Victorian crisis would now drive unemployment into double digits and wipe up to $12 billion, or 2.5 per cent, from GDP in the three months to the end of September.