The UK government claims that Scottish independence will cost the taxpayer hundreds of pounds more each year as the state pension bill will rise for each working-age adult.
According to the Department of Work and Pensions (DWP), which based its analysis on the Scottish National Party's (SNP) pledges, an independent Scotland will cost an extra £450 (€547, $756) per working age adult until around 2030.
"This country has a long history of a strong welfare state, which we can rightly be proud of," said Work and Pensions Secretary Iain Duncan Smith.
"As part of the UK, Scottish people benefit from this resilient and unified system, which delivers the same support everywhere irrespective of peaks and troughs in economies of the nations or demographic differences.
"Proposals by the Scottish Government would risk the well-being of vulnerable people who are currently supported by this system.
"On top of the ageing population, which is increasing faster in Scotland than the rest of the UK, the Scottish Government are committing to spending even more on wider welfare without saying how they'll pay for it."
The DWP also warned Scotland to not be complacent over how much all UK taxpayers cough up for their welfare system.
DWP's data shows that Scotland's benefits bill, including childcare and tax credit, totalled £17.7bn in 2012-13, which equates to £60 more per person than in the UK as a whole.
The UK government's data follows closely after Britain's former Prime Minister Gordon Brown warned of a ticking 'time bomb' when it comes to Scottish pensions as the retired are "better protected" as part of the UK.
As part of his speech for the Better Together rally, the Labour party minister said that Scotland needs to stay part of the UK, in order to share "risks and resources" when it comes to their savings.
"In fact the real debate is between two Scottish visions of Scotland's future," said Brown.
"The nationalist one based on the breaking of all political links with the UK, and our vision based on a strong Scottish Parliament backed up by a system of pooling and sharing risks and resources across the UK.
"The whole point of sharing risks and resources across the UK is that it is right and proper that the British welfare state bears the rising cost of Scottish pensions as the number of old people will rise from one million to 1.3 million."
Scottish people will vote in an independence referendum on 18 September this year and will be asked the straight "yes/no" question: "Should Scotland be an independent country?"
The referendum period starts on 30 May.
Meanwhile, SNP's Deputy First Minister Nicola Sturgeon hit back at Whitehall's figures.
"Welfare spending and pensions are more affordable in Scotland than the UK because they account for a smaller proportion of our tax revenues and national income," said Sturgeon.
"But now a Tory-led government that Scotland didn't vote for is dismantling large parts of the post-war welfare state because of its right-wing ideology.
"This is social vandalism on a vast scale and shows why people are worse off when decisions about Scotland are taken at Westminster."