Shoppers in England will face a 5p charge for plastic bags under a new government plan to be announced by Nick Clegg.
The scheme, intended to discourage the use of environmentally-damaging carrier bags, will be set out by the Deputy Prime Minister as the Liberal Democrat conference opens in Glasgow.
Mr Clegg is understood to have fought hard for the policy in the coalition, despite government concerns about the rising cost of living.
"Nick Clegg had to fight pretty hard in government to deliver this when everything is about the cost of living," a senior Lib Dem source said.
"We believe that a small charge outweighs the environmental damage caused by plastic bags."
The charge will only apply to supermarkets and other large stores, with small corner shops excluded.
The proceeds will go to charities involved in clearing up the environmental damage caused by the bags rather than the Government or the retailers.
Liberal Democrat Energy and Climate Change Secretary Ed Davey told the BBC the move "is a huge environmental step forward."
"We are very clear that none of this money will come to government, we are not trying to tax people, we are trying to change people's behaviour, encourage much more environmentally-friendly behaviour," he said.
The move, which is set to come into effect in autumn 2015 after the next general election, will bring England into line with other parts of the UK.
Charges are already in place in Wales - where there has been a 76% fall in plastic bag use since it was introduced in 2011 - and Northern Ireland, with Scotland to follow suit next year.
Northern Ireland's Environment Minister, Mark H Durkan, this week announced he was not going ahead with plans to raise the levy to 10p per bag, because the present arrangements were proving successful.
He said data from major supermarkets showed there had been an 80% reduction in plastic bag use since the levy was brought in.Suggest a correction