We examine Australia’s Mature Age Worker Tax offset (MAWTO), a targeted earned income tax credit of up to $500 to incentivize participation of older workers that existed from 2004-05 to 2014-15. Using a difference-in-differences approach, we find that MAWTO increased labor market participation by around 0.5 percentage points. For women only, it had a small impact on earnings of about 1.5 per cent. We estimate that the average cost for each person induced to work longer is between $37,000 and $78,000.