Chancellor George Osborne will give details of how the government will cut 3% of spending over the next four years.
The BBC's political editor Nick Robinson told Today presenter John Humphrys that people will not know at the end of today whether their job or service will go. But he added that, although the details of cuts are yet to be worked out, many people should know what the changes will mean for welfare payments and pensions.
Economics editor Stephanie Flanders said that the challenge faced by the Comprehensive Spending Review was to impose a real cut in public expenditure when more money was being spent on debt interest, social security and pensions and on the NHS, which might now account for a third of all government expenditure.
She added that the success of the spending review "is going to depend in large part on what it does to the economic recovery. There has been a debate that's not going to be resolved today, whether there is a risk in making these cuts".
Get in touch with Today via
or text us on 84844.