Many people believe that Social Security in the USA, and National Insurance in the UK, are separate from general government expenditure. After all, in the US, Social Security has its own 'trust fund' from which it is supposed to pay for benefits. Similarly, in the UK, the National Insurance Fund is supposed to take care of benefits. Both at present show heavy surpluses, but are expected to 'run out' by the middle of the century. The surpluses have prompted some people (notably pensioners' groups) to campaign for the money to be spent on bigger benefits for the beneficiaries. See for example this article in the New York Times about how the US Social Security Trust Fund is "going to run out".

The problem is that these "surpluses" are no more than an accounting trick. The money in the funds is in invested in Government bonds, and so it represents simultaneously both an asset and a liability - the government borrows money from itself, and promises to pay itself back later (from revenues it gets in general taxation of course). It's completely meaningless. The 1% rise in National Insurance Contributions was 'to pay for the NHS', but what actually happened to the money was that half of the extra revenue was spent on the NHS; the other half of it simply went to reduce the amount Gordon Brown was borrowing by buying the government's own bonds.

This kind of thing is almost exactly what Enron and Worldcom did in the private sector. If a private company does it, it is at the very least dodgy and likely illegal. Why do we let the government continue to get away with it?