The beeb have a useful analysis of the UK deficit situation. The Tories would like to claim that the deficit is going down and that so too is the UKs debt levels. Actually, thats not strictly speaking true as it requires a very selective view of the UK economy. The deficit, borrowing and overall debt levels have all increased under the Tories, despite aggressive tory budget cuts. There is certainly a possibility that sometime around 2017, if current trends continue, that the economic indicators might well turn a corner.
However that requires us to make a number of assumptions, such as Tories welfare cuts dont impact on the economy, that the present economic recovery continues, that the UK doesnt leave the EU and that Scotland doesnt leave the UK. And to be blunt none of these factors are guaranteed.