Employers will be allowed to claim an inability to pay the rates agreed under the wage-setting system for low-paid staff, the Irish Independent has learned.
Sunday premium pay for those covered by the Joint Labour Committees (JLCs) will also be scrapped.
The controversial new rules governing the wages in the catering, hotels, retail, grocery, contract cleaning and some other sectors will be announced today.
Ahead of the publication, the Labour Party was accused last night of capitulating in an attack on the low paid.
Under the reforms to the JLCs, low-paid staff will be entitled to the same protection as other employees for working on a Sunday.
The existing Organisation of Working Time Act allows for staff to be compensated for working on Sunday through the negotiation of extra pay, an increased average wage across the week or a day off in lieu.
In reality, though, the scrapping of the Sunday premium payments will mean a pay cut for staff in those sectors who work on that day.
The number of JLC agreements is also widely expected to be reduced substantially.
Jobs Minister Richard Bruton is understood to have struck a deal with Tanaiste Eamon Gilmore, granting some concessions from his original proposals.
After coming under attack from the Labour Party, Mr Bruton is believed to have got through the bulk of his proposals.
The minister's hand was strengthened substantially by a High Court ruling that JLCs were unconstitutional and pressure from the IMF and EU to reform the area.
The new deal will have to be cleared with the troika lending Ireland the €85bn bailout.
The Government is also believed to have accepted the recommendation on the introduction of an inability-to-pay clause for employers.
The expert report on the area said there should be a "derogation on economic grounds" introduced, where the employer can claim it would damage the viability of the firm and cause job losses if they had to pay the rates agreed.
The United Left Alliance said the deal was done "in a time-honoured and cowardly manner", announced while the Dail wasn't sitting and just before ministers took holidays.