Reduced Sunday penalty rates will be phased in over the next few years.

The Fair Work Commission is cutting penalty rates for fast food, hospitality, retail and pharmacy employees, which will be phased in until 2020.

Workers in fast food and hospitality will have Sunday penalty rates reduced by 5 per cent this year, and 10 per cent in 2018 and 2019.

It will leave the final rate at 125 and 150 per cent respectively.

Retail or pharmacy sector workers will have their Sunday pay cut by 5 per cent this year and a further 15 per cent every year until 2020.

Australian Council of Trade Unions (ACTU) secretary Sally McManus said it was still devastating for families.

“They're looking at offsetting it in the first year and [if] you look at the cuts in the following years they're much bigger, especially in some of the industries, which is a 15 per cent pay cut in the out years,” she said.

“I think no matter which way you dress it up, you're facing pay cuts every single year.”