I highly recommend this oped, which sensibly concludes:
This brings us back to personal Social Security accounts. Every dollar that goes into those accounts rather than into the Treasury is an extra dollar that Uncle Sam has to borrow. So if we’re going to keep up cash accounting for the government, let’s be consistent. If you want to consider personal accounts as an investment that doesn’t increase the deficit, you have to treat the Treasury IOUs issued to federal trust funds as an expense and add them to the deficit. Then taxpayers will have an idea of what’s really going on.