Labor has branded the Coalition's views on the minimum wage "medieval", but Malcolm Turnbull says the government's controversial submission to the Fair Work Commission is no different from those lodged under Julia Gillard.

The government's submission to the annual wage review has urged the commission to take a cautious approach, warning any "excessive" pay rises for the low-paid could imperil job creation.

The opposition claimed the Coalition is effectively arguing against a pay rise for nearly 200,000 people paid the minimum wage - $17.70 an hour or 672.70 for a 38-hour week - and was quick to seize on a section of the government submission that noted "low-paid workers are often found in high-income households".

Pressed about that claim during a testy radio interview, Employment Minister Michaelia Cash was unable to articulate how many low-paid workers lived in high-income households. But later in the Senate she said it was "just under 50 per cent".