If you're under age 59 1/2 and need to do distributions from your IRA periodically you'll want to speak with your tax advisor. We have been getting a lot of questions on this topic especially from IRA owners who have seen their portfolio go down dramatically in 2008.  72t is complicated and you'll want an expert to advise you!

Here's a quick recap on 72t and information on changing the calculation method from Financial-Planning.com:

In order to avoid a 10% penalty on IRA withdrawals before age 591/2, many early retirees take a series of substantially equal periodic payments (SOSEPP). If they do not maintain SOSEPP for five years or until they reach age 591/2, whichever comes later, all early IRA withdrawals are subject to the 10% surtax.

The IRS has approved three methods for calculating a SOSEPP: amortization, annuitization and minimum distribution. In practice, most people choose either the amortization or annuitization methods, both of which permit relatively large penalty-free withdrawals.

Another option is available to early retirees now as a result of the 2000-2002 bear market, when IRAs also dwindled. In response, the IRS issued Revenue Ruling 2002-62. This option permits taxpayers using the amortization or annuitization methods to make a onetime switch to the minimum distribution method. Such a switch allows the SOSEPP to continue, penalty-free, with much smaller distributions

Switching methods in this manner allows taxpayers to avoid retroactive penalties and penalties on those penalties, but it cuts sharply into the amount an early retiree can draw from the IRA.

RetirementThink 72t information.