This Easter break will be the final major holiday period before staff affected by upcoming penalty rate cuts are dealt a tough financial blow, the peak body representing workers says.

The Australian Council of Trade Unions says due to cuts to penalty and public holiday pay, next Easter will mean tens of millions of dollars per day in lost wages.

ACTU secretary Sally McManus will speak on the issue in Melbourne on Thursday morning, following news of controversial cuts that affect workers in the hospitality, retail, fast food and pharmacy sectors.

The government has estimated 300,000 to 450,000 workers will be affected by cuts recommended by the Fair Work Commission.

However the federal opposition says up to 700,000 people who rely on Sunday and public holiday penalty rates will be directly hit by the changes, which could also flow on to other workers.

The penalty rate cuts are due to be implemented on July 1.

Stationery retailer, Kikki.K, is the first to secure a workplace deal that factors in penalty rate reductions.

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