Inflation could be back within the Reserve Bank’s 2 per cent to 3 per cent target band by Christmas, due to a new round of cost of living assistance and slower growth next financial year, Tuesday’s federal budget will forecast.

The new inflation forecasts, which revive chances for a pre-election interest rate cut, are markedly lower than those issued by the RBA last week, but Treasurer Jim Chalmers said the discrepancy was a result of the board not knowing what was in the budget.