As I write, the price of a barrel of crude oil is below $60.

That's a relief for motorists but bad news for jobs, especially in the north-east of Scotland. But it also has a huge impact on the debate about the funding of Scotland's NHS and schools.

Today, along with Shadow Chancellor Ed Balls, I will meet in London senior figures from the oil industry to talk about what we are demanding from the UK Budget when George Osborne delivers it next week. There can be no tinkering around the edges. The Chancellor must deliver a fiscal regime that will attract the investment needed to sustain the oil industry in the long-term.

As we know, though, the low oil price doesn't just affect the thousands of workers in Scotland's oil industry. It tells us something vital about how Scotland's public services and pensions can be made secure for the future.

Tomorrow the SNP Edinburgh Government will publish Scotland's accounts for the last year. This will look at how much tax is raised in Scotland and how much public money is spent in areas such as schools, hospitals and pensions. The plummeting oil price has had an impact on how much tax is raised from the North Sea and our ability as a nation to pay for public services.

This really matters because of the SNP's General Election plan for full fiscal autonomy within the UK. This would mean scrapping the Barnett Formula, which for decades has meant the stability of higher public spending on schools and hospitals, and the guaranteed UK funding of pensions and replacing them both with a reliance on volatile oil taxes.

This week Labour's support for the continuation of the Barnett Formula versus the SNP's plans for full fiscal autonomy will be centre stage. The Nationalists want to pay for Scotland's public services only out of taxes raised in Scotland, within the UK. By contrast Labour wants major new powers for the Scottish Parliament and the back-up of the higher and more stable public spending that comes from Barnett and guaranteed UK support for pensions.

We will know from the SNP's own figures tomorrow what impact scrapping Barnett and relying on oil would have on Scotland. If previous years are anything to go by, losing that extra share of UK tax revenue through Barnett would be devastating for our ability to pay for our schools and hospitals. We would also be replacing a UK-wide pension with a separate Scottish one that would be at the mercy of plummeting oil prices.

This isn't about re-running the arguments from the referendum debate. The General Election is now about the best form of devolution for Scotland within the UK.

The Scottish Affairs Committee says the SNP's plan for full fiscal autonomy would cost Scotland at least £6.5 billion immediately. That's not just austerity, it's austerity max. Having been subjected to Tory austerity for five years, the last thing that Scotland now needs is to risk the funding of our schools and hospitals on the wild fluctuations in oil prices.

That would be a dreadful development for Scotland. Having paid into the UK pot for years, the SNP want us to give up Barnett at the very moment we need it most.

We need to move away the Tory austerity agenda that would take us back to 1930s levels of public spending. And we need to reject the austerity-max that would come from the SNP's plan for full fiscal autonomy within the UK.

Scottish Labour has a better plan for Scotland. Instead of putting our schools and hospitals at risk we want to increase the taxes of the wealthiest few across the UK to fund 1,000 more nurses in Scotland's NHS and establish a £125 million fund to help the working class kids being left behind by the SNP Government in Edinburgh.

Tomorrow's public accounts will be a big moment in the context of the future of Scotland and the UK as a whole. The choice facing Scots will become clearer than ever. Only Labour has a different approach to the failed Tory austerity and the new austerity of the SNP's fiscal autonomy.