Universal benefits for pensioners will be protected for almost a year after the 2015 general election, Downing Street has said.
The statement comes amid speculation that the winter fuel allowance and other payments could be means-tested under a new round of spending cuts.
Some cabinet members say wealthier pensioners should be targeted.
But Number 10's announcement extends David Cameron's previous pledge on the benefits by 11 months to April 2016.
Mr Cameron's vow to preserve the benefits, which also include free TV licences and bus passes, was initially made during the 2010 general election campaign.
It later formed part of the 2010 Coalition Agreement, which sets out the government's policy framework for this Parliament.
Ministers have just begun negotiating the next round of spending settlements covering the 2015-16 financial year, with Chancellor George Osborne already saying he is looking for £10bn in additional savings to the welfare budget.
Some Lib Dems and Conservative members of the cabinet feel universal pensioner benefits are an area which should now be looked at. Deputy Prime Minister Nick Clegg, for instance, suggested that the better off could afford to "sacrifice" some of their benefits before the poorest are affected.
Questioned about the speculation, Downing Street initially said the benefits would only be protected until the next general election, set for May 2015.
This was later clarified by the prime minister's official spokesman who said: "As regards pensioner benefits, the prime minister has very clearly set out his promises on this. He stands fully behind them.
"Pensioner benefits are fully protected for the entirety of this Parliament - including for the year 2015-16."