The document provides new evidence of continuing rivalry between Mr Brown and Tony Blair. It underlines the Old Labour credentials which the Chancellor has sought recently to strengthen through closer links with party members and trade unionists.
Labour has also invited businesses to discuss the reforms at a series of seminars in its headquarters in Millbank Tower. They will pay more than pounds 100 each to take part.
Drawn up by a group chaired by the Chancellor, the paper says that in future all public spending decisions must be focused on cutting poverty. It will form the basis of Labour's manifesto on welfare for the next general election.
The document from the party's commission on welfare hints that tax cuts for the middle classes will not be on the agenda. Instead, it promises a better deal for the poorest.
Every Whitehall department must be brought into a crusade to make Britain a fairer place for those who cannot work, it adds.
"Public spending decisions will form part of the Government's overall anti-poverty strategy... All services should be mobilised to tackle poverty - benefits, childcare, health, housing, social services, employment services, education and transport."
The paper underlines the principles on which Beveridge set up the Welfare State 50 years ago, and says Labour still holds them dear.
"The welfare system has not kept pace with change. As a result, it is failing in its historic mission of creating a fairer and more prosperous society," it says.
The Welfare Policy Commission is chaired by Mr Brown and attended by Harriet Harman, the Secretary of State for Social Security, the Employment Minister Andrew Smith, and several senior trade unionists.
Behind the "big idea" of easing poverty through public spending are a range of new initiatives designed to modernise the welfare system. In future, claimants may be able to apply for benefits via the Internet as well as using websites to search for jobs that might be suitable for them. Front-line benefits staff may also be brought into the policy-making process to inject ideas from the grass-roots of the system.
Labour is also planning two public campaigns. The first will aim to convince people that initiatives to cut benefit fraud are right in principle. Ministers have been stung by the level of suspicion and bad feeling generated by schemes such as the Benefits Integrity Project, under which some disabled people have had their benefits cut.
The second campaign will try to cut levels of teenage pregnancies by improving children's knowledge of responsible relationships and good parenting.
The change of emphasis underlines a subtle shift since Labour came to power. Two months before the general election David Blunkett, now Secretary of State for Education, said in a lecture that the idea of straightforward redistribution was outdated.
"Any government entering the 21st century cannot hope to create a more equal or egalitarian society simply by taking money from one set of people and redistributing it to others," he said. Last month, though, he praised the Government for what he called a "quiet redistribution" through improved opportunities.
One Cabinet source said last night that the change had taken place despite, rather than because of, the Prime Minister's stance on poverty and social exclusion. Opposition to cuts in lone parent benefits, which caused a backbench rebellion last Autumn, had brought a change of emphasis, he said.
"The idea that tackling poverty is a key issue for this government is much more prevalent than we thought it might be six months ago ... some of this is almost despite the centre rather than because of it. It is surprising for some of us, but certainly genuine."
A senior trade unionist also welcomed the change of stance. "This will give a lot of hope to all the party members who thought Labour had somehow abandoned welfare in the process of reform," he said.
Ed Balls' column, page 19Reuse content