You comment alone Sir, needs its own blog post. Pretty interesting. My accountant never told me this.
If anyone is doing this, or interested in doing this, the way they deal with these cases is as follows: he picks a number based on a combination of what salary surveys say and what kind of mood he is in, multiplies it by 7 (since you've probably been doing this for 7 years by the time he gets it, which is how far they can go back), and assesses that as unreported income. They then tack on penalties and interest for the tax liability of said income. That makes for a really bad day.