Any child in England whose parents receive Universal Credit will be able to claim free school meals from September 2026, the government has said.
Parents on the credit will be eligible regardless of their income. Currently, their household must earn less than £7,400 a year to qualify.
The government says the change will make 500,000 more pupils eligible, which the prime minister said would "help families who need it most".
Labour has faced scrutiny over plans to tackle child poverty, and is yet to decide whether to scrap the two-child benefit cap.
Education Secretary Bridget Phillipson told the BBC ministers were "working as quickly as we can" on next year's plans to extend free school meals.
Ministers said the changes to free school meals would save parents £500 a year and "lift 100,000 children out of poverty".
On the two-child benefit cap, which prevents most families from claiming means-tested benefits for any third or additional children born after April 2017, Phillipson was asked if there were plans to change this policy.
The education secretary told BBC Breakfast it was not a "silver bullet" but "it was on the table."
She has previously said the government is looking at scrapping it but that it would cost a lot of money.
On free school meals, the Department for Education has set aside £1bn to fund the change up to 2029.
They have also pledged £13m to a dozen food charities across England to "fight food poverty", by redistributing food from farms.
Sir Keir Starmer said: "Feeding more children every day, for free, is one of the biggest interventions we can make to put more money in parents' pockets, tackle the stain of poverty, and set children up to learn."...read more