Treasury is forecasting a spike in people claiming investment tax breaks this financial year as experts said higher interest rates and more onerous costs on landlords imposed by some state governments were pushing investors to offload properties.

The department’s latest tax expenditure statement estimates forgone taxes from the capital gains tax discount will hit $22.7 billion in 2024-25, up from $9.2 billion four years earlier. The figure for this year is more than double the Treasury forecast published in February last year.