A planned overhaul of workers’ rights would give millions of people the right to claim unpaid parental leave and stronger protections from unfair dismissal from their first day in a job.

The government is set to announce the details of its Employment Rights Bill, which it says would end the “exploitative” use of zero-hours contracts and “fire and rehire” practices.

Deputy Prime Minister Angela Rayner described this as the “biggest upgrade to rights at work for a generation”.

There are 28 separate measures in the bill to be introduced later, most of which will be subject to further consultation and will not take effect before autumn 2026.

The government is seeking to be pro-worker and pro-business and striking that balance means that much of the detail is still to be decided.

While some unions have welcomed the announcement, business groups have expressed concerns about how the changes will work in practice.

As part of the plans, the existing two-year qualifying period for protections from unfair dismissal will be removed and workers will have them from their very first day in a new job.

Ministers have said this would benefit some nine million workers who have been with their current employer for less than two years.

• Statutory sick pay (SSP): Workers will be entitled to SSP from the first day they are ill, rather than the fourth day
• Lower earnings limit for SSP: Currently, workers earning less than £123 per week cannot claim SSP. This limit will be removed but the bill will set out a lesser level of sick pay for lower earners
• Paternity leave: Fathers to be eligible from day one of employment, instead of 26 weeks
• Unpaid parental leave: Parents to be eligible from day one of employment, instead of one year
• Unpaid bereavement leave: To become a “day one” right for workers
• Flexible working: Bosses will be expected to consider any flexible working requests made from day one, and say yes unless they can prove it is unreasonable

Roughly 30,000 fathers or partners will be eligible for paternity leave as a result, while 1.5 million parents will have the right to unpaid leave from day one under the changes.

“Too many people are drawn into a race to the bottom, denied the security they need to raise a family while businesses are unable to retain the workers they need to grow,” Ms Rayner said.

“We’re raising the floor on rights at work to deliver a stronger, fairer and brighter future of work for Britain.”

The government will also consult on a new statutory probation period for new hires.

While Business Secretary Jonathan Reynolds had previously suggested the new legislation would mean a maximum probation period of about six months for most businesses, it has proven a tricky subject during discussions.

Some trade unions are worried that a short period of probation could make firms reluctant to take on new staff, or even cut jobs.

Dominic Ponniah, the boss of Cleanology, told the BBC his firm is delaying hiring plans while being more cautious of who it takes on.

The cleaning company he runs has about 1,300 employees located from Scotland to Southampton.

“Hiring people is quite a big thing, costly, and people are concerned about the ramifications after these announcements,” he said.

“It’s just another thing that businesses have to contend with,” he said, adding that the new rules around sick pay, unfair dismissal and probationary periods would make business “very, very nervous”.

Tina McKenzie, policy chair at the Federation of Small Businesses suggested that the new bill was a “rushed job, clumsy, chaotic and poorly planned”.

She said that smaller firms would be left “scrabbling to make sense” of the changes and called for a full consultation on each individual measure.

The matter of zero-hours contracts has also been hotly debated.

Under the Employment Rights Bill, bosses will have to offer workers a guaranteed-hours contract based on the hours they have clocked up during a 12-week period.

Workers on zero-hours contracts will also be entitled to “reasonable” notice ahead of any changes being made to their shifts, as well as compensation if a shift is cancelled or ended early.

Zero-hours contracts have come in for criticism in the past as the likes of factory or warehouse workers have missed out on a steady income and certain benefits.

But UKHospitality said it is the preferred policy for workers in their sector.

Ruby, a first-year university student, told the BBC that she is on a zero-hours contract with her local football club, selling food and drinks on match days.

“In my situation it’s quite good. I can pick up shifts if and when I need a bit of extra money, or if I’m home for the weekend,” she said.

She says that this approach offers her more flexibility than a contract specifying a certain number of hours would.

“If I’m there and I want to do it, I can do it.”

The business secretary said on Thursday it was “vital” to give employers flexibility to grow, while ending what he described as “unscrupulous and unfair practices”.

Gary Smith, general secretary of the GMB union, described the bill as a “groundbreaking first step to giving workers the rights they’ve been denied for so long”.

But he added that there is a “long way to go”, and called for unions and workers to be involved in the discussions around the new legislation.

“The legislation must be watertight and without loopholes that could be used by those wanting to delay the rights workers so desperately need,” he said.

Some measures included in Labour’s plan to “Make Work Pay”, issued in the run-up to the General Election, will not feature in the bill either.

The “right to switch off”, for example, will be part of a “Next Steps” document in which the government will set out hopes for further reform.

Conservative shadow business secretary Kevin Hollinrake said that the party would look “closely” at the detail of what Labour has set out.

“But businesses and the economy needs certainty not the threat of being sent back to the 1970s, unleashing waves of low threshold, zero warning strikes, driving down growth and slowing productivity,” he said.

Additional reporting by Emer Moreau.