"The number of people in poverty will rise from 10.2 million in 2015 to 13.8 million in 2030, an increase of 3.6 million. For children the increase is 1.2 million, from 2.5 million to 3.7 million," the report says.
According to the report, the earnings of high income households will rise 11 times faster than the earnings of the low income households in Britain in the course of the next 15 years.
The Fabian Society warns that "unless the next government takes dramatic action, the UK will be much less equal in 2030 than it is today."
The report suggests a strategy that, according to the Labor-affiliated think tank, could help avoid the rise in poverty.
The recommendations for the next UK government include raising the national minimum wage to 60 percent of median earnings by 2020, rejecting major benefit cuts for low and middle income households and improving employment opportunities.
The Fabian Society is a British think tank affiliated to the Labor Party.
The next general election in Britain is due to be held on May 7, 2015 to choose the 56th Parliament of the United Kingdom.