Today's report completely undermines the SNP's case for independence, which so far has centred on their claim that if we were independent we'd have more money to spend.
Not only do the SNP's own economic advisers say that Scotland has spent more money than we've raised in every year in the last 21 except one, but now independent and impartial experts at the IFS have said that we'd have to raise taxes or cut spending, or possibly both, if we separate from the rest of the UK. The IFS estimates spending cuts worth around £6billion, or income tax rises of up to 9%.
The reason for this is that just as the tax we get from the North Sea is declining, the cost of looking after an increasing number of older people is rising. This means that if we leave the UK the burden of filling this gap will fall on the shoulders of around five million people in Scotland alone, rather than being spread across the UK's population of over 60million people.
Crucially, the IFS note that rather than face up to the consequences of independence for our public finances, the SNP only tell us that they would spend more money. Whether it's renationalisation of the Royal Mail, cutting corporation tax for big business, increasing the value of the state pension or lowering the retirement age, the SNP pretend that in an independent Scotland would be awash with cash to spend. Today's IFS report comprehensively demolishes that claim.
The choice we face is clear - believe Alex Salmond or believe the experts and the facts.
As part of the UK, we are better placed to tackle the long term challenge of sustainable public finances. Things are difficult just now, but the IFS report makes clear that they would get much worse if we separated from the UK. That is a risk that we really don't need to take.
Coming little more than a week before the publication of the SNP's crucial White Paper, the IFS report poses a significant challenge for Alex Salmond. The White Paper must face up to the consequences of independence, including the need for big spending cuts and tax rises. If it doesn't, then it won't be worth the paper it is written on.
Alistair Darling is the Chair of Better Together and Labour MP for Edinburgh South West - this blog first appeared on the Better Together campaign blog, and can be read here