This is interesting. At some companies, highly compensated executives -- CEOs, VPs, and other corner-office types -- are granted special 401(k)s to help them salt away more than the $15,000 limit everyone else has to live by.

The so-called "mirror" 401(k)s, also known as spillover 401ks, are a type of deferred retirement vehicle for people who get paid a lot. After the $15,000 limit for a standard 401(k) is reached (for the 2006 tax year), contributions continue into the mirror 401(k) up to an additional $15,000. This money can be withdrawn upon retirement.

That's according to the new IRS rules. Under the old system, withdrawals started at retirement, but executives could contribute as much as they wanted to the mirror 401k.

From a tax perspective, the new system is far more restrictive for people whose salaries are in the hundreds of thousands or millions of dollars. On the other hand, if you're making that much money, you'll probably have a significant cash and investment safety net -- albeit a taxable one -- by the time you retire.mortgage calculator